From 996b1bfa95347e5171c3f7ab32b6740656ed7a8b Mon Sep 17 00:00:00 2001
From: nagachika <nagachika@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Wed, 24 Aug 2016 15:28:23 +0000
Subject: merge revision(s) 53707,53708,53709,53712,53777,53781: [Backport
 #12326]

	* lib/rubygems.rb, lib/rubygems/*, test/rubygems/*: Update rubygems-2.5.2.
	  It supports to enable frozen string literal and add `--norc` option for
	  disable to `.gemrc` configuration.
	  See 2.5.2 release notes for other fixes and enhancements.
	  https://github.com/rubygems/rubygems/blob/a8aa3bac723f045c52471c7b9328310a048561e0/History.txt#L3

	* lib/rubygems/specification.rb: `coding` is affect only first line except
	  shebang.

	* lib/rubygems/package.rb, lib/rubygems/package/*: ditto.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@56003 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 lib/rubygems/available_set.rb                      |  2 +-
 lib/rubygems/basic_specification.rb                |  9 ++--
 lib/rubygems/command.rb                            | 10 ++--
 lib/rubygems/command_manager.rb                    |  2 +-
 lib/rubygems/commands/build_command.rb             |  6 ++-
 lib/rubygems/commands/cert_command.rb              |  2 +-
 lib/rubygems/commands/check_command.rb             |  2 +-
 lib/rubygems/commands/cleanup_command.rb           |  2 +-
 lib/rubygems/commands/contents_command.rb          |  2 +-
 lib/rubygems/commands/dependency_command.rb        |  6 +--
 lib/rubygems/commands/environment_command.rb       |  7 ++-
 lib/rubygems/commands/fetch_command.rb             |  2 +-
 lib/rubygems/commands/generate_index_command.rb    |  2 +-
 lib/rubygems/commands/help_command.rb              |  2 +-
 lib/rubygems/commands/install_command.rb           |  2 +-
 lib/rubygems/commands/list_command.rb              |  2 +-
 lib/rubygems/commands/lock_command.rb              |  2 +-
 lib/rubygems/commands/mirror_command.rb            |  2 +-
 lib/rubygems/commands/open_command.rb              |  2 +-
 lib/rubygems/commands/outdated_command.rb          |  2 +-
 lib/rubygems/commands/owner_command.rb             |  2 +-
 lib/rubygems/commands/pristine_command.rb          |  2 +-
 lib/rubygems/commands/push_command.rb              |  2 +-
 lib/rubygems/commands/query_command.rb             | 18 ++++---
 lib/rubygems/commands/rdoc_command.rb              |  2 +-
 lib/rubygems/commands/search_command.rb            |  2 +-
 lib/rubygems/commands/server_command.rb            |  2 +-
 lib/rubygems/commands/setup_command.rb             |  2 +-
 lib/rubygems/commands/sources_command.rb           |  2 +-
 lib/rubygems/commands/specification_command.rb     |  2 +-
 lib/rubygems/commands/stale_command.rb             |  2 +-
 lib/rubygems/commands/uninstall_command.rb         |  2 +-
 lib/rubygems/commands/unpack_command.rb            |  2 +-
 lib/rubygems/commands/update_command.rb            |  2 +-
 lib/rubygems/commands/which_command.rb             |  2 +-
 lib/rubygems/commands/yank_command.rb              | 27 ++++------
 lib/rubygems/compatibility.rb                      |  2 +-
 lib/rubygems/config_file.rb                        | 11 ++--
 lib/rubygems/core_ext/kernel_gem.rb                |  2 +-
 lib/rubygems/core_ext/kernel_require.rb            |  2 +-
 lib/rubygems/defaults.rb                           |  2 +-
 lib/rubygems/dependency.rb                         |  6 +--
 lib/rubygems/dependency_installer.rb               |  2 +-
 lib/rubygems/dependency_list.rb                    |  2 +-
 lib/rubygems/deprecate.rb                          |  2 +-
 lib/rubygems/doctor.rb                             |  2 +-
 lib/rubygems/errors.rb                             |  2 +-
 lib/rubygems/exceptions.rb                         |  5 +-
 lib/rubygems/ext.rb                                |  2 +-
 lib/rubygems/ext/build_error.rb                    |  2 +-
 lib/rubygems/ext/builder.rb                        |  2 +-
 lib/rubygems/ext/cmake_builder.rb                  |  2 +-
 lib/rubygems/ext/configure_builder.rb              |  2 +-
 lib/rubygems/ext/ext_conf_builder.rb               | 20 +++++--
 lib/rubygems/ext/rake_builder.rb                   |  2 +-
 lib/rubygems/gem_runner.rb                         |  2 +-
 lib/rubygems/gemcutter_utilities.rb                | 13 +++--
 lib/rubygems/indexer.rb                            |  2 +-
 lib/rubygems/install_default_message.rb            |  2 +-
 lib/rubygems/install_message.rb                    |  2 +-
 lib/rubygems/install_update_options.rb             |  7 ++-
 lib/rubygems/installer.rb                          | 18 ++++---
 lib/rubygems/installer_test_case.rb                |  2 +-
 lib/rubygems/local_remote_options.rb               |  4 +-
 lib/rubygems/mock_gem_ui.rb                        |  2 +-
 lib/rubygems/name_tuple.rb                         |  4 +-
 lib/rubygems/package.rb                            |  6 +--
 lib/rubygems/package/digest_io.rb                  |  2 +-
 lib/rubygems/package/file_source.rb                |  2 +-
 lib/rubygems/package/io_source.rb                  |  2 +-
 lib/rubygems/package/old.rb                        |  9 ++--
 lib/rubygems/package/source.rb                     |  2 +-
 lib/rubygems/package/tar_header.rb                 |  3 +-
 lib/rubygems/package/tar_reader.rb                 |  3 +-
 lib/rubygems/package/tar_reader/entry.rb           |  2 +-
 lib/rubygems/package/tar_test_case.rb              |  2 +-
 lib/rubygems/package/tar_writer.rb                 |  2 +-
 lib/rubygems/package_task.rb                       |  2 +-
 lib/rubygems/path_support.rb                       | 21 +++++---
 lib/rubygems/platform.rb                           |  2 +-
 lib/rubygems/psych_additions.rb                    |  2 +-
 lib/rubygems/psych_tree.rb                         |  2 +-
 lib/rubygems/rdoc.rb                               |  2 +-
 lib/rubygems/remote_fetcher.rb                     |  2 +-
 lib/rubygems/request.rb                            |  6 +--
 lib/rubygems/request/connection_pools.rb           |  2 +-
 lib/rubygems/request/http_pool.rb                  |  2 +-
 lib/rubygems/request/https_pool.rb                 |  2 +-
 lib/rubygems/request_set.rb                        | 23 ++++----
 lib/rubygems/request_set/gem_dependency_api.rb     | 61 +++++++++++++++++++---
 lib/rubygems/request_set/lockfile.rb               |  7 ++-
 lib/rubygems/request_set/lockfile/parser.rb        | 28 ++++++----
 lib/rubygems/request_set/lockfile/tokenizer.rb     |  2 +-
 lib/rubygems/requirement.rb                        |  2 +-
 lib/rubygems/resolver.rb                           |  3 +-
 lib/rubygems/resolver/activation_request.rb        | 24 ++++++---
 lib/rubygems/resolver/api_set.rb                   |  2 +-
 lib/rubygems/resolver/api_specification.rb         |  2 +-
 lib/rubygems/resolver/best_set.rb                  |  2 +-
 lib/rubygems/resolver/composed_set.rb              |  2 +-
 lib/rubygems/resolver/conflict.rb                  |  2 +-
 lib/rubygems/resolver/current_set.rb               |  2 +-
 lib/rubygems/resolver/dependency_request.rb        |  2 +-
 lib/rubygems/resolver/git_set.rb                   |  2 +-
 lib/rubygems/resolver/git_specification.rb         |  2 +-
 lib/rubygems/resolver/index_set.rb                 |  2 +-
 lib/rubygems/resolver/index_specification.rb       |  2 +-
 lib/rubygems/resolver/installed_specification.rb   |  2 +-
 lib/rubygems/resolver/installer_set.rb             |  2 +-
 lib/rubygems/resolver/local_specification.rb       |  2 +-
 lib/rubygems/resolver/lock_set.rb                  | 10 ++--
 lib/rubygems/resolver/lock_specification.rb        |  9 ++--
 lib/rubygems/resolver/molinillo.rb                 |  2 +-
 lib/rubygems/resolver/molinillo/lib/molinillo.rb   |  6 ++-
 .../molinillo/lib/molinillo/dependency_graph.rb    | 11 +++-
 .../resolver/molinillo/lib/molinillo/errors.rb     |  7 ++-
 .../molinillo/lib/molinillo/gem_metadata.rb        |  5 +-
 .../molinillo/modules/specification_provider.rb    |  2 +-
 .../resolver/molinillo/lib/molinillo/modules/ui.rb |  2 +-
 .../resolver/molinillo/lib/molinillo/resolution.rb |  3 +-
 .../resolver/molinillo/lib/molinillo/resolver.rb   |  5 +-
 .../resolver/molinillo/lib/molinillo/state.rb      | 16 +++---
 lib/rubygems/resolver/requirement_list.rb          |  2 +-
 lib/rubygems/resolver/set.rb                       |  2 +-
 lib/rubygems/resolver/source_set.rb                | 48 +++++++++++++++++
 lib/rubygems/resolver/spec_specification.rb        |  2 +-
 lib/rubygems/resolver/specification.rb             |  2 +-
 lib/rubygems/resolver/stats.rb                     |  2 +-
 lib/rubygems/resolver/vendor_set.rb                |  2 +-
 lib/rubygems/resolver/vendor_specification.rb      |  2 +-
 lib/rubygems/security.rb                           |  2 +-
 lib/rubygems/security/policies.rb                  |  2 +-
 lib/rubygems/security/policy.rb                    |  5 +-
 lib/rubygems/security/signer.rb                    |  2 +-
 lib/rubygems/security/trust_dir.rb                 |  2 +-
 lib/rubygems/server.rb                             |  2 +-
 lib/rubygems/source.rb                             |  2 +-
 lib/rubygems/source/git.rb                         |  2 +-
 lib/rubygems/source/installed.rb                   |  2 +-
 lib/rubygems/source/local.rb                       |  2 +-
 lib/rubygems/source/lock.rb                        |  2 +-
 lib/rubygems/source/specific_file.rb               |  2 +-
 lib/rubygems/source/vendor.rb                      |  2 +-
 lib/rubygems/source_list.rb                        |  4 +-
 lib/rubygems/source_local.rb                       |  2 +-
 lib/rubygems/source_specific_file.rb               |  2 +-
 lib/rubygems/spec_fetcher.rb                       |  2 +-
 lib/rubygems/specification.rb                      | 18 ++++---
 lib/rubygems/stub_specification.rb                 |  2 +-
 lib/rubygems/syck_hack.rb                          |  2 +-
 lib/rubygems/test_case.rb                          | 19 +++++--
 lib/rubygems/test_utilities.rb                     |  2 +-
 lib/rubygems/text.rb                               |  3 +-
 lib/rubygems/uninstaller.rb                        |  2 +-
 lib/rubygems/uri_formatter.rb                      |  2 +-
 lib/rubygems/user_interaction.rb                   |  2 +-
 lib/rubygems/util.rb                               |  4 +-
 lib/rubygems/util/licenses.rb                      | 15 +++++-
 lib/rubygems/util/list.rb                          |  2 +-
 lib/rubygems/validator.rb                          |  2 +-
 lib/rubygems/version.rb                            |  7 ++-
 lib/rubygems/version_option.rb                     |  2 +-
 162 files changed, 501 insertions(+), 291 deletions(-)
 create mode 100644 lib/rubygems/resolver/source_set.rb

(limited to 'lib/rubygems')

diff --git a/lib/rubygems/available_set.rb b/lib/rubygems/available_set.rb
index da43cdf3fb..49b5d5fd06 100644
--- a/lib/rubygems/available_set.rb
+++ b/lib/rubygems/available_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 class Gem::AvailableSet
 
   include Enumerable
diff --git a/lib/rubygems/basic_specification.rb b/lib/rubygems/basic_specification.rb
index db962c6dcd..5c57076f91 100644
--- a/lib/rubygems/basic_specification.rb
+++ b/lib/rubygems/basic_specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # BasicSpecification is an abstract class which implements some common code
 # used by both Specification and StubSpecification.
@@ -125,9 +125,9 @@ class Gem::BasicSpecification
 
   def full_name
     if platform == Gem::Platform::RUBY or platform.nil? then
-      "#{name}-#{version}".untaint
+      "#{name}-#{version}".dup.untaint
     else
-      "#{name}-#{version}-#{platform}".untaint
+      "#{name}-#{version}-#{platform}".dup.untaint
     end
   end
 
@@ -282,7 +282,7 @@ class Gem::BasicSpecification
              self.require_paths.first
            end
 
-    "#{self.full_gem_path}/#{dirs}".untaint
+    "#{self.full_gem_path}/#{dirs}".dup.untaint
   end
 
   ##
@@ -326,4 +326,3 @@ class Gem::BasicSpecification
   end
 
 end
-
diff --git a/lib/rubygems/command.rb b/lib/rubygems/command.rb
index 28af3d090c..5b41fc288e 100644
--- a/lib/rubygems/command.rb
+++ b/lib/rubygems/command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -154,7 +154,7 @@ class Gem::Command
 
   def show_lookup_failure(gem_name, version, errors, domain)
     if errors and !errors.empty?
-      msg = "Could not find a valid gem '#{gem_name}' (#{version}), here is why:\n"
+      msg = "Could not find a valid gem '#{gem_name}' (#{version}), here is why:\n".dup
       errors.each { |x| msg << "          #{x.wordy}\n" }
       alert_error msg
     else
@@ -540,6 +540,11 @@ class Gem::Command
                     'Turn on Ruby debugging') do
   end
 
+  add_common_option('--norc',
+                    'Avoid loading any .gemrc file') do
+  end
+
+
   # :stopdoc:
 
   HELP = <<-HELP
@@ -580,4 +585,3 @@ end
 
 module Gem::Commands
 end
-
diff --git a/lib/rubygems/command_manager.rb b/lib/rubygems/command_manager.rb
index 95e846e340..451b719c46 100644
--- a/lib/rubygems/command_manager.rb
+++ b/lib/rubygems/command_manager.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/commands/build_command.rb b/lib/rubygems/commands/build_command.rb
index facc5226af..38c45e46f0 100644
--- a/lib/rubygems/commands/build_command.rb
+++ b/lib/rubygems/commands/build_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/package'
 
@@ -42,6 +42,10 @@ with gem spec:
   def execute
     gemspec = get_one_gem_name
 
+    unless File.exist? gemspec
+      gemspec += '.gemspec' if File.exist? gemspec + '.gemspec'
+    end
+
     if File.exist? gemspec then
       spec = Gem::Specification.load gemspec
 
diff --git a/lib/rubygems/commands/cert_command.rb b/lib/rubygems/commands/cert_command.rb
index 073c6bd195..7adf5b01b1 100644
--- a/lib/rubygems/commands/cert_command.rb
+++ b/lib/rubygems/commands/cert_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/security'
 begin
diff --git a/lib/rubygems/commands/check_command.rb b/lib/rubygems/commands/check_command.rb
index 9d2b086951..818cb05f55 100644
--- a/lib/rubygems/commands/check_command.rb
+++ b/lib/rubygems/commands/check_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/version_option'
 require 'rubygems/validator'
diff --git a/lib/rubygems/commands/cleanup_command.rb b/lib/rubygems/commands/cleanup_command.rb
index a0bb3d576a..46f89f1bb8 100644
--- a/lib/rubygems/commands/cleanup_command.rb
+++ b/lib/rubygems/commands/cleanup_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/dependency_list'
 require 'rubygems/uninstaller'
diff --git a/lib/rubygems/commands/contents_command.rb b/lib/rubygems/commands/contents_command.rb
index de756939c0..e0f2eedb5d 100644
--- a/lib/rubygems/commands/contents_command.rb
+++ b/lib/rubygems/commands/contents_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'English'
 require 'rubygems/command'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/dependency_command.rb b/lib/rubygems/commands/dependency_command.rb
index b9e33a94e0..97fd812ffa 100644
--- a/lib/rubygems/commands/dependency_command.rb
+++ b/lib/rubygems/commands/dependency_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/version_option'
@@ -100,7 +100,7 @@ use with other commands.
   end
 
   def display_readable specs, reverse # :nodoc:
-    response = ''
+    response = String.new
 
     specs.each do |spec|
       response << print_dependencies(spec)
@@ -153,7 +153,7 @@ use with other commands.
   end
 
   def print_dependencies(spec, level = 0) # :nodoc:
-    response = ''
+    response = String.new
     response << '  ' * level + "Gem #{spec.full_name}\n"
     unless spec.dependencies.empty? then
       spec.dependencies.sort_by { |dep| dep.name }.each do |dep|
diff --git a/lib/rubygems/commands/environment_command.rb b/lib/rubygems/commands/environment_command.rb
index 47b62f03af..e825c761ad 100644
--- a/lib/rubygems/commands/environment_command.rb
+++ b/lib/rubygems/commands/environment_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 
 class Gem::Commands::EnvironmentCommand < Gem::Command
@@ -72,7 +72,7 @@ lib/rubygems/defaults/operating_system.rb
   end
 
   def execute
-    out = ''
+    out = String.new
     arg = options[:args][0]
     out <<
       case arg
@@ -104,7 +104,7 @@ lib/rubygems/defaults/operating_system.rb
   end
 
   def show_environment # :nodoc:
-    out = "RubyGems Environment:\n"
+    out = "RubyGems Environment:\n".dup
 
     out << "  - RUBYGEMS VERSION: #{Gem::VERSION}\n"
 
@@ -158,4 +158,3 @@ lib/rubygems/defaults/operating_system.rb
   end
 
 end
-
diff --git a/lib/rubygems/commands/fetch_command.rb b/lib/rubygems/commands/fetch_command.rb
index 3aecdc3b08..19559a7774 100644
--- a/lib/rubygems/commands/fetch_command.rb
+++ b/lib/rubygems/commands/fetch_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/generate_index_command.rb b/lib/rubygems/commands/generate_index_command.rb
index c0fadba64f..01f1f88405 100644
--- a/lib/rubygems/commands/generate_index_command.rb
+++ b/lib/rubygems/commands/generate_index_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/indexer'
 
diff --git a/lib/rubygems/commands/help_command.rb b/lib/rubygems/commands/help_command.rb
index 4c176f372e..de3f175fad 100644
--- a/lib/rubygems/commands/help_command.rb
+++ b/lib/rubygems/commands/help_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 
 class Gem::Commands::HelpCommand < Gem::Command
diff --git a/lib/rubygems/commands/install_command.rb b/lib/rubygems/commands/install_command.rb
index 6e243df441..5f0934aa17 100644
--- a/lib/rubygems/commands/install_command.rb
+++ b/lib/rubygems/commands/install_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/install_update_options'
 require 'rubygems/dependency_installer'
diff --git a/lib/rubygems/commands/list_command.rb b/lib/rubygems/commands/list_command.rb
index 1f85cd3fcd..1acb49e5fb 100644
--- a/lib/rubygems/commands/list_command.rb
+++ b/lib/rubygems/commands/list_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/commands/query_command'
 
diff --git a/lib/rubygems/commands/lock_command.rb b/lib/rubygems/commands/lock_command.rb
index 5a56e91933..3eebfadc05 100644
--- a/lib/rubygems/commands/lock_command.rb
+++ b/lib/rubygems/commands/lock_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 
 class Gem::Commands::LockCommand < Gem::Command
diff --git a/lib/rubygems/commands/mirror_command.rb b/lib/rubygems/commands/mirror_command.rb
index 3816876a92..801c9c8927 100644
--- a/lib/rubygems/commands/mirror_command.rb
+++ b/lib/rubygems/commands/mirror_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 
 unless defined? Gem::Commands::MirrorCommand
diff --git a/lib/rubygems/commands/open_command.rb b/lib/rubygems/commands/open_command.rb
index 63bff16db0..957d369b26 100644
--- a/lib/rubygems/commands/open_command.rb
+++ b/lib/rubygems/commands/open_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'English'
 require 'rubygems/command'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/outdated_command.rb b/lib/rubygems/commands/outdated_command.rb
index f7cfc08f70..70f6c02801 100644
--- a/lib/rubygems/commands/outdated_command.rb
+++ b/lib/rubygems/commands/outdated_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/spec_fetcher'
diff --git a/lib/rubygems/commands/owner_command.rb b/lib/rubygems/commands/owner_command.rb
index b002ff18d4..e507c988d6 100644
--- a/lib/rubygems/commands/owner_command.rb
+++ b/lib/rubygems/commands/owner_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/gemcutter_utilities'
diff --git a/lib/rubygems/commands/pristine_command.rb b/lib/rubygems/commands/pristine_command.rb
index 991272ae85..a5a348dc72 100644
--- a/lib/rubygems/commands/pristine_command.rb
+++ b/lib/rubygems/commands/pristine_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/package'
 require 'rubygems/installer'
diff --git a/lib/rubygems/commands/push_command.rb b/lib/rubygems/commands/push_command.rb
index a8e0819e82..035a03e5e7 100644
--- a/lib/rubygems/commands/push_command.rb
+++ b/lib/rubygems/commands/push_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/gemcutter_utilities'
diff --git a/lib/rubygems/commands/query_command.rb b/lib/rubygems/commands/query_command.rb
index 4782eb98ef..d6196b44ed 100644
--- a/lib/rubygems/commands/query_command.rb
+++ b/lib/rubygems/commands/query_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/spec_fetcher'
@@ -50,6 +50,12 @@ class Gem::Commands::QueryCommand < Gem::Command
       options[:all] = value
     end
 
+    add_option('-e', '--exact',
+               'Name of gem(s) to query on matches the',
+               'provided STRING') do |value, options|
+      options[:exact] = value
+    end
+
     add_option(      '--[no-]prerelease',
                'Display prerelease versions') do |value, options|
       options[:prerelease] = value
@@ -79,7 +85,8 @@ is too hard to use.
     elsif !options[:name].source.empty?
       name = Array(options[:name])
     else
-      name = options[:args].to_a.map{|arg| /#{arg}/i }
+      args = options[:args].to_a
+      name = options[:exact] ? args : args.map{|arg| /#{arg}/i }
     end
 
     prerelease = options[:prerelease]
@@ -162,7 +169,7 @@ is too hard to use.
                :latest
              end
 
-      if name.source.empty?
+      if name.respond_to?(:source) && name.source.empty?
         spec_tuples = fetcher.detect(type) { true }
       else
         spec_tuples = fetcher.detect(type) do |name_tuple|
@@ -277,7 +284,7 @@ is too hard to use.
   end
 
   def spec_authors entry, spec
-    authors = "Author#{spec.authors.length > 1 ? 's' : ''}: "
+    authors = "Author#{spec.authors.length > 1 ? 's' : ''}: ".dup
     authors << spec.authors.join(', ')
     entry << format_text(authors, 68, 4)
   end
@@ -291,7 +298,7 @@ is too hard to use.
   def spec_license entry, spec
     return if spec.license.nil? or spec.license.empty?
 
-    licenses = "License#{spec.licenses.length > 1 ? 's' : ''}: "
+    licenses = "License#{spec.licenses.length > 1 ? 's' : ''}: ".dup
     licenses << spec.licenses.join(', ')
     entry << "\n" << format_text(licenses, 68, 4)
   end
@@ -341,4 +348,3 @@ is too hard to use.
   end
 
 end
-
diff --git a/lib/rubygems/commands/rdoc_command.rb b/lib/rubygems/commands/rdoc_command.rb
index 72aa972017..6992040dca 100644
--- a/lib/rubygems/commands/rdoc_command.rb
+++ b/lib/rubygems/commands/rdoc_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/version_option'
 require 'rubygems/rdoc'
diff --git a/lib/rubygems/commands/search_command.rb b/lib/rubygems/commands/search_command.rb
index 06cc997d4c..933436d84d 100644
--- a/lib/rubygems/commands/search_command.rb
+++ b/lib/rubygems/commands/search_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/commands/query_command'
 
diff --git a/lib/rubygems/commands/server_command.rb b/lib/rubygems/commands/server_command.rb
index f41bda40da..245156d50d 100644
--- a/lib/rubygems/commands/server_command.rb
+++ b/lib/rubygems/commands/server_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/server'
 
diff --git a/lib/rubygems/commands/setup_command.rb b/lib/rubygems/commands/setup_command.rb
index d3ef9ef94e..ebb08d24d7 100644
--- a/lib/rubygems/commands/setup_command.rb
+++ b/lib/rubygems/commands/setup_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 
 ##
diff --git a/lib/rubygems/commands/sources_command.rb b/lib/rubygems/commands/sources_command.rb
index 0ff5e075f5..9832afd214 100644
--- a/lib/rubygems/commands/sources_command.rb
+++ b/lib/rubygems/commands/sources_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/remote_fetcher'
 require 'rubygems/spec_fetcher'
diff --git a/lib/rubygems/commands/specification_command.rb b/lib/rubygems/commands/specification_command.rb
index 4e291c6ab1..ad8840adc2 100644
--- a/lib/rubygems/commands/specification_command.rb
+++ b/lib/rubygems/commands/specification_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/stale_command.rb b/lib/rubygems/commands/stale_command.rb
index 6930c1cfde..0524ee1e2b 100644
--- a/lib/rubygems/commands/stale_command.rb
+++ b/lib/rubygems/commands/stale_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 
 class Gem::Commands::StaleCommand < Gem::Command
diff --git a/lib/rubygems/commands/uninstall_command.rb b/lib/rubygems/commands/uninstall_command.rb
index 52d4450bfb..fe97790194 100644
--- a/lib/rubygems/commands/uninstall_command.rb
+++ b/lib/rubygems/commands/uninstall_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/version_option'
 require 'rubygems/uninstaller'
diff --git a/lib/rubygems/commands/unpack_command.rb b/lib/rubygems/commands/unpack_command.rb
index 08eaf01314..ffa429de6f 100644
--- a/lib/rubygems/commands/unpack_command.rb
+++ b/lib/rubygems/commands/unpack_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/installer'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/update_command.rb b/lib/rubygems/commands/update_command.rb
index 8d76a8ce8e..d654a5fa4e 100644
--- a/lib/rubygems/commands/update_command.rb
+++ b/lib/rubygems/commands/update_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/command_manager'
 require 'rubygems/dependency_installer'
diff --git a/lib/rubygems/commands/which_command.rb b/lib/rubygems/commands/which_command.rb
index c01dc18ee0..c028d5d49f 100644
--- a/lib/rubygems/commands/which_command.rb
+++ b/lib/rubygems/commands/which_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 
 class Gem::Commands::WhichCommand < Gem::Command
diff --git a/lib/rubygems/commands/yank_command.rb b/lib/rubygems/commands/yank_command.rb
index ec99bd7df6..0d6575b272 100644
--- a/lib/rubygems/commands/yank_command.rb
+++ b/lib/rubygems/commands/yank_command.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/version_option'
@@ -32,7 +32,7 @@ as the reason for the removal request.
   end
 
   def usage # :nodoc:
-    "#{program_name} GEM -v VERSION [-p PLATFORM] [--undo] [--key KEY_NAME]"
+    "#{program_name} GEM -v VERSION [-p PLATFORM] [--key KEY_NAME] [--host HOST]"
   end
 
   def initialize
@@ -41,25 +41,25 @@ as the reason for the removal request.
     add_version_option("remove")
     add_platform_option("remove")
 
-    add_option('--undo') do |value, options|
-      options[:undo] = true
+    add_option('--host HOST',
+               'Yank from another gemcutter-compatible host') do |value, options|
+      options[:host] = value
     end
 
     add_key_option
+    @host = nil
   end
 
   def execute
-    sign_in
+    @host = options[:host]
+
+    sign_in @host
 
     version   = get_version_from_requirements(options[:version])
     platform  = get_platform_from_requirements(options)
 
     if version then
-      if options[:undo] then
-        unyank_gem(version, platform)
-      else
-        yank_gem(version, platform)
-      end
+      yank_gem(version, platform)
     else
       say "A version argument is required: #{usage}"
       terminate_interaction
@@ -71,16 +71,11 @@ as the reason for the removal request.
     yank_api_request(:delete, version, platform, "api/v1/gems/yank")
   end
 
-  def unyank_gem(version, platform)
-    say "Unyanking gem from #{host}..."
-    yank_api_request(:put, version, platform, "api/v1/gems/unyank")
-  end
-
   private
 
   def yank_api_request(method, version, platform, api)
     name = get_one_gem_name
-    response = rubygems_api_request(method, api) do |request|
+    response = rubygems_api_request(method, api, host) do |request|
       request.add_field("Authorization", api_key)
 
       data = {
diff --git a/lib/rubygems/compatibility.rb b/lib/rubygems/compatibility.rb
index d09ddb6bf8..2056b5b53a 100644
--- a/lib/rubygems/compatibility.rb
+++ b/lib/rubygems/compatibility.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # :stopdoc:
 
 #--
diff --git a/lib/rubygems/config_file.rb b/lib/rubygems/config_file.rb
index 30f26db8c9..de90cbfd65 100644
--- a/lib/rubygems/config_file.rb
+++ b/lib/rubygems/config_file.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -201,11 +201,12 @@ class Gem::ConfigFile
       result.merge load_file file
     end
 
-
     @hash = operating_system_config.merge platform_config
-    @hash = @hash.merge system_config
-    @hash = @hash.merge user_config
-    @hash = @hash.merge environment_config
+    unless arg_list.index '--norc'
+      @hash = @hash.merge system_config
+      @hash = @hash.merge user_config
+      @hash = @hash.merge environment_config
+    end
 
     # HACK these override command-line args, which is bad
     @backtrace                  = @hash[:backtrace]                  if @hash.key? :backtrace
diff --git a/lib/rubygems/core_ext/kernel_gem.rb b/lib/rubygems/core_ext/kernel_gem.rb
index 07376784e6..b0dd69bfcc 100644
--- a/lib/rubygems/core_ext/kernel_gem.rb
+++ b/lib/rubygems/core_ext/kernel_gem.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # RubyGems adds the #gem method to allow activation of specific gem versions
 # and overrides the #require method on Kernel to make gems appear as if they
diff --git a/lib/rubygems/core_ext/kernel_require.rb b/lib/rubygems/core_ext/kernel_require.rb
index 196db5b6ee..6c00f3fd9b 100755
--- a/lib/rubygems/core_ext/kernel_require.rb
+++ b/lib/rubygems/core_ext/kernel_require.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/defaults.rb b/lib/rubygems/defaults.rb
index c1d45c19e6..16fa96eb2d 100644
--- a/lib/rubygems/defaults.rb
+++ b/lib/rubygems/defaults.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Gem
   DEFAULT_HOST = "https://rubygems.org"
 
diff --git a/lib/rubygems/dependency.rb b/lib/rubygems/dependency.rb
index c0ab87d965..c7b2451c6a 100644
--- a/lib/rubygems/dependency.rb
+++ b/lib/rubygems/dependency.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The Dependency class holds a Gem name and a Gem::Requirement.
 
@@ -307,9 +307,9 @@ class Gem::Dependency
 
       if specs.empty?
         total = Gem::Specification.to_a.size
-        msg   = "Could not find '#{name}' (#{requirement}) among #{total} total gem(s)\n"
+        msg   = "Could not find '#{name}' (#{requirement}) among #{total} total gem(s)\n".dup
       else
-        msg   = "Could not find '#{name}' (#{requirement}) - did find: [#{specs.join ','}]\n"
+        msg   = "Could not find '#{name}' (#{requirement}) - did find: [#{specs.join ','}]\n".dup
       end
       msg << "Checked in 'GEM_PATH=#{Gem.path.join(File::PATH_SEPARATOR)}', execute `gem env` for more information"
 
diff --git a/lib/rubygems/dependency_installer.rb b/lib/rubygems/dependency_installer.rb
index 954e2bf984..28848f7373 100644
--- a/lib/rubygems/dependency_installer.rb
+++ b/lib/rubygems/dependency_installer.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems'
 require 'rubygems/dependency_list'
 require 'rubygems/package'
diff --git a/lib/rubygems/dependency_list.rb b/lib/rubygems/dependency_list.rb
index 8e00dc94c8..35fe7c4c1a 100644
--- a/lib/rubygems/dependency_list.rb
+++ b/lib/rubygems/dependency_list.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/deprecate.rb b/lib/rubygems/deprecate.rb
index 54ab02830c..375194c1e8 100644
--- a/lib/rubygems/deprecate.rb
+++ b/lib/rubygems/deprecate.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Provides a single method +deprecate+ to be used to declare when
 # something is going away.
diff --git a/lib/rubygems/doctor.rb b/lib/rubygems/doctor.rb
index 15f05f63fa..ec4a16c3f8 100644
--- a/lib/rubygems/doctor.rb
+++ b/lib/rubygems/doctor.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems'
 require 'rubygems/user_interaction'
 
diff --git a/lib/rubygems/errors.rb b/lib/rubygems/errors.rb
index b22cd07706..8304647546 100644
--- a/lib/rubygems/errors.rb
+++ b/lib/rubygems/errors.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # This file contains all the various exceptions and other errors that are used
 # inside of RubyGems.
diff --git a/lib/rubygems/exceptions.rb b/lib/rubygems/exceptions.rb
index 0c741a2d01..9089eae4d5 100644
--- a/lib/rubygems/exceptions.rb
+++ b/lib/rubygems/exceptions.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # TODO: the documentation in here is terrible.
 #
 # Each exception needs a brief description and the scenarios where it is
@@ -138,7 +138,7 @@ class Gem::ImpossibleDependenciesError < Gem::Exception
     requester  = requester ? requester.spec.full_name : 'The user'
     dependency = @request.dependency
 
-    message = "#{requester} requires #{dependency} but it conflicted:\n"
+    message = "#{requester} requires #{dependency} but it conflicted:\n".dup
 
     @conflicts.each do |_, conflict|
       message << conflict.explanation
@@ -268,4 +268,3 @@ end
 # Backwards compatible typo'd exception class for early RubyGems 2.0.x
 
 Gem::UnsatisfiableDepedencyError = Gem::UnsatisfiableDependencyError # :nodoc:
-
diff --git a/lib/rubygems/ext.rb b/lib/rubygems/ext.rb
index 4640b668f0..18d2bc233a 100644
--- a/lib/rubygems/ext.rb
+++ b/lib/rubygems/ext.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/ext/build_error.rb b/lib/rubygems/ext/build_error.rb
index 2098026b05..0b3c17a9a0 100644
--- a/lib/rubygems/ext/build_error.rb
+++ b/lib/rubygems/ext/build_error.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Raised when there is an error while building extensions.
 
diff --git a/lib/rubygems/ext/builder.rb b/lib/rubygems/ext/builder.rb
index d79b3a5901..699903ab0e 100644
--- a/lib/rubygems/ext/builder.rb
+++ b/lib/rubygems/ext/builder.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/ext/cmake_builder.rb b/lib/rubygems/ext/cmake_builder.rb
index 7bf431c37e..efa3bd1d88 100644
--- a/lib/rubygems/ext/cmake_builder.rb
+++ b/lib/rubygems/ext/cmake_builder.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/command'
 
 class Gem::Ext::CmakeBuilder < Gem::Ext::Builder
diff --git a/lib/rubygems/ext/configure_builder.rb b/lib/rubygems/ext/configure_builder.rb
index b732cada57..8b42bf7ee9 100644
--- a/lib/rubygems/ext/configure_builder.rb
+++ b/lib/rubygems/ext/configure_builder.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/ext/ext_conf_builder.rb b/lib/rubygems/ext/ext_conf_builder.rb
index 2b50b08dc9..59e243b972 100644
--- a/lib/rubygems/ext/ext_conf_builder.rb
+++ b/lib/rubygems/ext/ext_conf_builder.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -12,9 +12,20 @@ class Gem::Ext::ExtConfBuilder < Gem::Ext::Builder
   FileEntry = FileUtils::Entry_ # :nodoc:
 
   def self.build(extension, directory, dest_path, results, args=[], lib_dir=nil)
-    # relative path required as some versions of mktmpdir return an absolute
-    # path which breaks make if it includes a space in the name
-    tmp_dest = get_relative_path(Dir.mktmpdir(".gem.", "."))
+    tmp_dest = Dir.mktmpdir(".gem.", ".")
+
+    # Some versions of `mktmpdir` return absolute paths, which will break make
+    # if the paths contain spaces. However, on Ruby 1.9.x on Windows, relative
+    # paths cause all C extension builds to fail.
+    #
+    # As such, we convert to a relative path unless we are using Ruby 1.9.x on
+    # Windows. This means that when using Ruby 1.9.x on Windows, paths with
+    # spaces do not work.
+    #
+    # Details: https://github.com/rubygems/rubygems/issues/977#issuecomment-171544940
+    #
+    # TODO: Make this unconditional when rubygems no longer supports Ruby 1.9.x.
+    tmp_dest = get_relative_path(tmp_dest) unless Gem.win_platform? && RUBY_VERSION <= '2.0'
 
     t = nil
     Tempfile.open %w"siteconf .rb", "." do |siteconf|
@@ -81,4 +92,3 @@ class Gem::Ext::ExtConfBuilder < Gem::Ext::Builder
   end
 
 end
-
diff --git a/lib/rubygems/ext/rake_builder.rb b/lib/rubygems/ext/rake_builder.rb
index 279117675a..682f1253e1 100644
--- a/lib/rubygems/ext/rake_builder.rb
+++ b/lib/rubygems/ext/rake_builder.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/gem_runner.rb b/lib/rubygems/gem_runner.rb
index 2bf8ac68bf..fec9e403da 100644
--- a/lib/rubygems/gem_runner.rb
+++ b/lib/rubygems/gem_runner.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/gemcutter_utilities.rb b/lib/rubygems/gemcutter_utilities.rb
index 98e78fe341..464993b11f 100644
--- a/lib/rubygems/gemcutter_utilities.rb
+++ b/lib/rubygems/gemcutter_utilities.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/remote_fetcher'
 
 ##
@@ -69,9 +69,14 @@ module Gem::GemcutterUtilities
       terminate_interaction 1 # TODO: question this
     end
 
-    if allowed_push_host and self.host != allowed_push_host
-      alert_error "#{self.host.inspect} is not allowed by the gemspec, which only allows #{allowed_push_host.inspect}"
-      terminate_interaction 1
+    if allowed_push_host
+      allowed_host_uri = URI.parse(allowed_push_host)
+      host_uri         = URI.parse(self.host)
+
+      unless (host_uri.scheme == allowed_host_uri.scheme) && (host_uri.host == allowed_host_uri.host)
+        alert_error "#{self.host.inspect} is not allowed by the gemspec, which only allows #{allowed_push_host.inspect}"
+        terminate_interaction 1
+      end
     end
 
     uri = URI.parse "#{self.host}/#{path}"
diff --git a/lib/rubygems/indexer.rb b/lib/rubygems/indexer.rb
index 21ccf0dfbb..871cc09d8d 100644
--- a/lib/rubygems/indexer.rb
+++ b/lib/rubygems/indexer.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems'
 require 'rubygems/package'
 require 'time'
diff --git a/lib/rubygems/install_default_message.rb b/lib/rubygems/install_default_message.rb
index d20a6c71a3..dc73fd962b 100644
--- a/lib/rubygems/install_default_message.rb
+++ b/lib/rubygems/install_default_message.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems'
 require 'rubygems/user_interaction'
 
diff --git a/lib/rubygems/install_message.rb b/lib/rubygems/install_message.rb
index da68b192b1..6880db583e 100644
--- a/lib/rubygems/install_message.rb
+++ b/lib/rubygems/install_message.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems'
 require 'rubygems/user_interaction'
 
diff --git a/lib/rubygems/install_update_options.rb b/lib/rubygems/install_update_options.rb
index 0466583e42..26c5e84d1f 100644
--- a/lib/rubygems/install_update_options.rb
+++ b/lib/rubygems/install_update_options.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -174,6 +174,11 @@ module Gem::InstallUpdateOptions
                 "meet version requirements") do |value, options|
       options[:minimal_deps] = true
     end
+
+    add_option(:"Install/Update", "--[no-]post-install-message",
+                "Print post install message") do |value, options|
+      options[:post_install_message] = value
+    end
   end
 
   ##
diff --git a/lib/rubygems/installer.rb b/lib/rubygems/installer.rb
index 7b4979d7ca..85358e0d1a 100644
--- a/lib/rubygems/installer.rb
+++ b/lib/rubygems/installer.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -213,7 +213,13 @@ class Gem::Installer
       next unless io.gets =~ /This file was generated by RubyGems/
 
       ruby_executable = true
-      existing = io.read.slice(/^gem (['"])(.*?)(\1),/, 2)
+      existing = io.read.slice(%r{
+          ^(
+            gem \s |
+            load \s Gem\.bin_path\(
+          )
+          (['"])(.*?)(\2),
+        }x, 3)
     end
 
     return if spec.name == existing
@@ -221,7 +227,7 @@ class Gem::Installer
     # somebody has written to RubyGems' directory, overwrite, too bad
     return if Gem.default_bindir != @bin_dir and not ruby_executable
 
-    question = "#{spec.name}'s executable \"#{filename}\" conflicts with "
+    question = "#{spec.name}'s executable \"#{filename}\" conflicts with ".dup
 
     if ruby_executable then
       question << existing
@@ -297,7 +303,7 @@ class Gem::Installer
       write_cache_file
     end
 
-    say spec.post_install_message unless spec.post_install_message.nil?
+    say spec.post_install_message if options[:post_install_message] && !spec.post_install_message.nil?
 
     Gem::Installer.install_lock.synchronize { Gem::Specification.reset }
 
@@ -627,7 +633,8 @@ class Gem::Installer
       :bin_dir      => nil,
       :env_shebang  => false,
       :force        => false,
-      :only_install_dir => false
+      :only_install_dir => false,
+      :post_install_message => true
     }.merge options
 
     @env_shebang         = options[:env_shebang]
@@ -712,7 +719,6 @@ if ARGV.first
   end
 end
 
-gem '#{spec.name}', version
 load Gem.bin_path('#{spec.name}', '#{bin_file_name}', version)
 TEXT
   end
diff --git a/lib/rubygems/installer_test_case.rb b/lib/rubygems/installer_test_case.rb
index 7a1b0aa5f0..bdefedc9f6 100644
--- a/lib/rubygems/installer_test_case.rb
+++ b/lib/rubygems/installer_test_case.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/test_case'
 require 'rubygems/installer'
 
diff --git a/lib/rubygems/local_remote_options.rb b/lib/rubygems/local_remote_options.rb
index 8d9e209771..597b87ea03 100644
--- a/lib/rubygems/local_remote_options.rb
+++ b/lib/rubygems/local_remote_options.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -24,7 +24,7 @@ module Gem::LocalRemoteOptions
         raise OptionParser::InvalidArgument, value
       end
 
-      unless ['http', 'https', 'file'].include?(uri.scheme)
+      unless ['http', 'https', 'file', 's3'].include?(uri.scheme)
          raise OptionParser::InvalidArgument, value
       end
 
diff --git a/lib/rubygems/mock_gem_ui.rb b/lib/rubygems/mock_gem_ui.rb
index 32e154c8b3..0223f8c35d 100644
--- a/lib/rubygems/mock_gem_ui.rb
+++ b/lib/rubygems/mock_gem_ui.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'stringio'
 require 'rubygems/user_interaction'
 
diff --git a/lib/rubygems/name_tuple.rb b/lib/rubygems/name_tuple.rb
index 1dc7f74112..316329a0bd 100644
--- a/lib/rubygems/name_tuple.rb
+++ b/lib/rubygems/name_tuple.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 #
 # Represents a gem of name +name+ at +version+ of +platform+. These
@@ -54,7 +54,7 @@ class Gem::NameTuple
       "#{@name}-#{@version}"
     else
       "#{@name}-#{@version}-#{@platform}"
-    end.untaint
+    end.dup.untaint
   end
 
   ##
diff --git a/lib/rubygems/package.rb b/lib/rubygems/package.rb
index 6b87475c78..0d9adba26e 100644
--- a/lib/rubygems/package.rb
+++ b/lib/rubygems/package.rb
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
@@ -59,7 +59,7 @@ class Gem::Package
       if source
         @path = source.path
 
-        message << " in #{path}" if path
+        message = message + " in #{path}" if path
       end
 
       super message
@@ -383,7 +383,7 @@ EOM
           FileUtils.chmod entry.header.mode, destination
         end if entry.file?
 
-        File.symlink(install_location(entry.header.linkname, destination_dir), destination) if entry.symlink?
+        File.symlink(entry.header.linkname, destination) if entry.symlink?
 
         verbose destination
       end
diff --git a/lib/rubygems/package/digest_io.rb b/lib/rubygems/package/digest_io.rb
index 47f76ec10d..4930c9aa7d 100644
--- a/lib/rubygems/package/digest_io.rb
+++ b/lib/rubygems/package/digest_io.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # IO wrapper that creates digests of contents written to the IO it wraps.
 
diff --git a/lib/rubygems/package/file_source.rb b/lib/rubygems/package/file_source.rb
index 4c2a7b9a4e..1a4dc4c824 100644
--- a/lib/rubygems/package/file_source.rb
+++ b/lib/rubygems/package/file_source.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The primary source of gems is a file on disk, including all usages
 # internal to rubygems.
diff --git a/lib/rubygems/package/io_source.rb b/lib/rubygems/package/io_source.rb
index 16a6e4be8b..ee79a21083 100644
--- a/lib/rubygems/package/io_source.rb
+++ b/lib/rubygems/package/io_source.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Supports reading and writing gems from/to a generic IO object.  This is
 # useful for other applications built on top of rubygems, such as
diff --git a/lib/rubygems/package/old.rb b/lib/rubygems/package/old.rb
index 1f1f33b856..5e722baa35 100644
--- a/lib/rubygems/package/old.rb
+++ b/lib/rubygems/package/old.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -64,7 +64,7 @@ class Gem::Package::Old < Gem::Package
 
         destination = install_location full_name, destination_dir
 
-        file_data = ''
+        file_data = String.new
 
         read_until_dashes io do |line|
           file_data << line
@@ -95,7 +95,7 @@ class Gem::Package::Old < Gem::Package
   # Reads the file list section from the old-format gem +io+
 
   def file_list io # :nodoc:
-    header = ''
+    header = String.new
 
     read_until_dashes io do |line|
       header << line
@@ -135,7 +135,7 @@ class Gem::Package::Old < Gem::Package
 
     return @spec if @spec
 
-    yaml = ''
+    yaml = String.new
 
     @gem.with_read_io do |io|
       skip_ruby io
@@ -176,4 +176,3 @@ class Gem::Package::Old < Gem::Package
   end
 
 end
-
diff --git a/lib/rubygems/package/source.rb b/lib/rubygems/package/source.rb
index 3dcce02a67..fe19776c38 100644
--- a/lib/rubygems/package/source.rb
+++ b/lib/rubygems/package/source.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 class Gem::Package::Source # :nodoc:
 end
 
diff --git a/lib/rubygems/package/tar_header.rb b/lib/rubygems/package/tar_header.rb
index 71529ee978..c54bd14d57 100644
--- a/lib/rubygems/package/tar_header.rb
+++ b/lib/rubygems/package/tar_header.rb
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
@@ -227,4 +227,3 @@ class Gem::Package::TarHeader
   end
 
 end
-
diff --git a/lib/rubygems/package/tar_reader.rb b/lib/rubygems/package/tar_reader.rb
index a1ea81cac4..1098336e36 100644
--- a/lib/rubygems/package/tar_reader.rb
+++ b/lib/rubygems/package/tar_reader.rb
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
@@ -121,4 +121,3 @@ class Gem::Package::TarReader
 end
 
 require 'rubygems/package/tar_reader/entry'
-
diff --git a/lib/rubygems/package/tar_reader/entry.rb b/lib/rubygems/package/tar_reader/entry.rb
index 59d167ee8e..5f958edc2f 100644
--- a/lib/rubygems/package/tar_reader/entry.rb
+++ b/lib/rubygems/package/tar_reader/entry.rb
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# frozen_string_literal: false
+# frozen_string_literal: true
 #++
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package/tar_test_case.rb b/lib/rubygems/package/tar_test_case.rb
index 3e494e5594..46ac949587 100644
--- a/lib/rubygems/package/tar_test_case.rb
+++ b/lib/rubygems/package/tar_test_case.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/test_case'
 require 'rubygems/package'
 
diff --git a/lib/rubygems/package/tar_writer.rb b/lib/rubygems/package/tar_writer.rb
index 6f1aab47a1..ab0313c9f8 100644
--- a/lib/rubygems/package/tar_writer.rb
+++ b/lib/rubygems/package/tar_writer.rb
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package_task.rb b/lib/rubygems/package_task.rb
index 0c525ad517..d554e3697b 100644
--- a/lib/rubygems/package_task.rb
+++ b/lib/rubygems/package_task.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # Copyright (c) 2003, 2004 Jim Weirich, 2009 Eric Hodel
 #
 # Permission is hereby granted, free of charge, to any person obtaining
diff --git a/lib/rubygems/path_support.rb b/lib/rubygems/path_support.rb
index 0ec29f8b60..afb559d472 100644
--- a/lib/rubygems/path_support.rb
+++ b/lib/rubygems/path_support.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 #
 # Gem::PathSupport facilitates the GEM_HOME and GEM_PATH environment settings
@@ -59,6 +59,9 @@ class Gem::PathSupport
         gem_path = gpaths.dup
       else
         gem_path = gpaths.split(Gem.path_separator)
+        if gpaths.end_with?(Gem.path_separator)
+          gem_path += default_path
+        end
       end
 
       if File::ALT_SEPARATOR then
@@ -69,13 +72,19 @@ class Gem::PathSupport
 
       gem_path << @home
     else
-      gem_path = Gem.default_path + [@home]
-
-      if defined?(APPLE_GEM_HOME)
-        gem_path << APPLE_GEM_HOME
-      end
+      gem_path = default_path
     end
 
     @path = gem_path.uniq
   end
+
+  # Return the default Gem path
+  def default_path
+    gem_path = Gem.default_path + [@home]
+
+    if defined?(APPLE_GEM_HOME)
+      gem_path << APPLE_GEM_HOME
+    end
+    gem_path
+  end
 end
diff --git a/lib/rubygems/platform.rb b/lib/rubygems/platform.rb
index cdc52cc9b3..d22d91ae54 100644
--- a/lib/rubygems/platform.rb
+++ b/lib/rubygems/platform.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require "rubygems/deprecate"
 
 ##
diff --git a/lib/rubygems/psych_additions.rb b/lib/rubygems/psych_additions.rb
index 487b269903..1ddd74421c 100644
--- a/lib/rubygems/psych_additions.rb
+++ b/lib/rubygems/psych_additions.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # This exists just to satisfy bugs in marshal'd gemspecs that
 # contain a reference to YAML::PrivateType. We prune these out
 # in Specification._load, but if we don't have the constant, Marshal
diff --git a/lib/rubygems/psych_tree.rb b/lib/rubygems/psych_tree.rb
index a5d306d769..41a7314b53 100644
--- a/lib/rubygems/psych_tree.rb
+++ b/lib/rubygems/psych_tree.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Gem
   if defined? ::Psych::Visitors
     class NoAliasYAMLTree < Psych::Visitors::YAMLTree
diff --git a/lib/rubygems/rdoc.rb b/lib/rubygems/rdoc.rb
index e9402ede76..7043bd2a31 100644
--- a/lib/rubygems/rdoc.rb
+++ b/lib/rubygems/rdoc.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems'
 require 'rubygems/user_interaction'
 require 'fileutils'
diff --git a/lib/rubygems/remote_fetcher.rb b/lib/rubygems/remote_fetcher.rb
index db1eed89d4..fda1e067ef 100644
--- a/lib/rubygems/remote_fetcher.rb
+++ b/lib/rubygems/remote_fetcher.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems'
 require 'rubygems/request'
 require 'rubygems/uri_formatter'
diff --git a/lib/rubygems/request.rb b/lib/rubygems/request.rb
index 3dfbc3d89c..7f2cb30e98 100644
--- a/lib/rubygems/request.rb
+++ b/lib/rubygems/request.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'net/http'
 require 'thread'
 require 'time'
@@ -156,7 +156,7 @@ class Gem::Request
           if Net::HTTPOK === incomplete_response
             reporter.fetch(file_name, incomplete_response.content_length)
             downloaded = 0
-            data = ''
+            data = String.new
 
             incomplete_response.read_body do |segment|
               data << segment
@@ -223,7 +223,7 @@ class Gem::Request
   end
 
   def user_agent
-    ua = "RubyGems/#{Gem::VERSION} #{Gem::Platform.local}"
+    ua = "RubyGems/#{Gem::VERSION} #{Gem::Platform.local}".dup
 
     ruby_version = RUBY_VERSION
     ruby_version += 'dev' if RUBY_PATCHLEVEL == -1
diff --git a/lib/rubygems/request/connection_pools.rb b/lib/rubygems/request/connection_pools.rb
index d22e357257..31fc609800 100644
--- a/lib/rubygems/request/connection_pools.rb
+++ b/lib/rubygems/request/connection_pools.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'thread'
 
 class Gem::Request::ConnectionPools # :nodoc:
diff --git a/lib/rubygems/request/http_pool.rb b/lib/rubygems/request/http_pool.rb
index ba3ab095bd..bfcd15399d 100644
--- a/lib/rubygems/request/http_pool.rb
+++ b/lib/rubygems/request/http_pool.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A connection "pool" that only manages one connection for now.  Provides
 # thread safe `checkout` and `checkin` methods.  The pool consists of one
diff --git a/lib/rubygems/request/https_pool.rb b/lib/rubygems/request/https_pool.rb
index 3ab91faf61..e82c2440e1 100644
--- a/lib/rubygems/request/https_pool.rb
+++ b/lib/rubygems/request/https_pool.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 class Gem::Request::HTTPSPool < Gem::Request::HTTPPool # :nodoc:
   private
 
diff --git a/lib/rubygems/request_set.rb b/lib/rubygems/request_set.rb
index b760a05d9b..5541e64b88 100644
--- a/lib/rubygems/request_set.rb
+++ b/lib/rubygems/request_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'tsort'
 
 ##
@@ -77,6 +77,11 @@ class Gem::RequestSet
 
   attr_reader :vendor_set # :nodoc:
 
+  ##
+  # The set of source gems imported via load_gemdeps.
+
+  attr_reader :source_set
+
   ##
   # Creates a RequestSet for a list of Gem::Dependency objects, +deps+.  You
   # can then #resolve and #install the resolved list of dependencies.
@@ -106,6 +111,7 @@ class Gem::RequestSet
     @sorted              = nil
     @specs               = nil
     @vendor_set          = nil
+    @source_set          = nil
 
     yield self if block_given?
   end
@@ -143,7 +149,6 @@ class Gem::RequestSet
       return requests
     end
 
-    cache_dir = options[:cache_dir] || Gem.dir
     @prerelease = options[:prerelease]
 
     requests = []
@@ -158,13 +163,11 @@ class Gem::RequestSet
         end
       end
 
-      path = req.download cache_dir
-
-      inst = Gem::Installer.at path, options
-
-      yield req, inst if block_given?
+      spec = req.spec.install options do |installer|
+        yield req, installer if block_given?
+      end
 
-      requests << inst.install
+      requests << spec
     end
 
     return requests if options[:gemdeps]
@@ -272,10 +275,11 @@ class Gem::RequestSet
   def load_gemdeps path, without_groups = [], installing = false
     @git_set    = Gem::Resolver::GitSet.new
     @vendor_set = Gem::Resolver::VendorSet.new
+    @source_set = Gem::Resolver::SourceSet.new
 
     @git_set.root_dir = @install_dir
 
-    lock_file = "#{File.expand_path(path)}.lock".untaint
+    lock_file = "#{File.expand_path(path)}.lock".dup.untaint
     begin
       tokenizer = Gem::RequestSet::Lockfile::Tokenizer.from_file lock_file
       parser = tokenizer.make_parser self, []
@@ -339,6 +343,7 @@ class Gem::RequestSet
     @sets << set
     @sets << @git_set
     @sets << @vendor_set
+    @sets << @source_set
 
     set = Gem::Resolver.compose_sets(*@sets)
     set.remote = @remote
diff --git a/lib/rubygems/request_set/gem_dependency_api.rb b/lib/rubygems/request_set/gem_dependency_api.rb
index 4927e5db6a..4b2699d7d2 100644
--- a/lib/rubygems/request_set/gem_dependency_api.rb
+++ b/lib/rubygems/request_set/gem_dependency_api.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A semi-compatible DSL for the Bundler Gemfile and Isolate gem dependencies
 # files.
@@ -205,6 +205,7 @@ class Gem::RequestSet::GemDependencyAPI
     @installing         = false
     @requires           = Hash.new { |h, name| h[name] = [] }
     @vendor_set         = @set.vendor_set
+    @source_set         = @set.source_set
     @gem_sources        = {}
     @without_groups     = []
 
@@ -363,6 +364,7 @@ class Gem::RequestSet::GemDependencyAPI
     source_set ||= gem_path       name, options
     source_set ||= gem_git        name, options
     source_set ||= gem_git_source name, options
+    source_set ||= gem_source     name, options
 
     duplicate = @dependencies.include? name
 
@@ -408,11 +410,7 @@ Gem dependencies file #{@path} requires #{name} more than once.
 
     pin_gem_source name, :git, repository
 
-    reference = nil
-    reference ||= options.delete :ref
-    reference ||= options.delete :branch
-    reference ||= options.delete :tag
-    reference ||= 'master'
+    reference = gem_git_reference options
 
     submodules = options.delete :submodules
 
@@ -421,6 +419,36 @@ Gem dependencies file #{@path} requires #{name} more than once.
     true
   end
 
+  ##
+  # Handles the git options from +options+ for git gem.
+  #
+  # Returns reference for the git gem.
+
+  def gem_git_reference options # :nodoc:
+    ref    = options.delete :ref
+    branch = options.delete :branch
+    tag    = options.delete :tag
+
+    reference = nil
+    reference ||= ref
+    reference ||= branch
+    reference ||= tag
+    reference ||= 'master'
+
+    if ref && branch
+      warn <<-WARNING
+Gem dependencies file #{@path} includes git reference for both ref and branch but only ref is used.
+      WARNING
+    end
+    if (ref||branch) && tag
+      warn <<-WARNING
+Gem dependencies file #{@path} includes git reference for both ref/branch and tag but only ref/branch is used.
+      WARNING
+    end
+
+    reference
+  end
+
   private :gem_git
 
   ##
@@ -481,6 +509,23 @@ Gem dependencies file #{@path} requires #{name} more than once.
 
   private :gem_path
 
+  ##
+  # Handles the source: option from +options+ for gem +name+.
+  #
+  # Returns +true+ if the source option was handled.
+
+  def gem_source name, options # :nodoc:
+    return unless source = options.delete(:source)
+
+    pin_gem_source name, :source, source
+
+    @source_set.add_source_gem name, source
+
+    true
+  end
+
+  private :gem_source
+
   ##
   # Handles the platforms: option from +options+.  Returns true if the
   # platform matches the current platform.
@@ -527,6 +572,7 @@ Gem dependencies file #{@path} requires #{name} more than once.
     else
       @requires[name] << name
     end
+    raise ArgumentError, "Unhandled gem options #{options.inspect}" unless options.empty?
   end
 
   private :gem_requires
@@ -612,6 +658,7 @@ Gem dependencies file #{@path} requires #{name} more than once.
 
     add_dependencies groups, spec.development_dependencies
 
+    @vendor_set.add_vendor_gem spec.name, path
     gem_requires spec.name, options
   end
 
@@ -651,6 +698,7 @@ Gem dependencies file #{@path} requires #{name} more than once.
       when :default then '(default)'
       when :path    then "path: #{source}"
       when :git     then "git: #{source}"
+      when :source  then "source: #{source}"
       else               '(unknown)'
       end
 
@@ -799,4 +847,3 @@ Gem dependencies file #{@path} requires #{name} more than once.
   Gem::RequestSet::GemDepedencyAPI = self # :nodoc:
 
 end
-
diff --git a/lib/rubygems/request_set/lockfile.rb b/lib/rubygems/request_set/lockfile.rb
index e9a706e83b..7f6eadb939 100644
--- a/lib/rubygems/request_set/lockfile.rb
+++ b/lib/rubygems/request_set/lockfile.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Parses a gem.deps.rb.lock file and constructs a LockSet containing the
 # dependencies found inside.  If the lock file is missing no LockSet is
@@ -130,8 +130,8 @@ class Gem::RequestSet::Lockfile
       [source.repository, source.rev_parse]
     end
 
-    out << "GIT"
     by_repository_revision.each do |(repository, revision), requests|
+      out << "GIT"
       out << "  remote: #{repository}"
       out << "  revision: #{revision}"
       out << "  specs:"
@@ -144,9 +144,8 @@ class Gem::RequestSet::Lockfile
           out << "      #{dep.name}#{dep.requirement.for_lockfile}"
         end
       end
+      out << nil
     end
-
-    out << nil
   end
 
   def relative_path_from dest, base # :nodoc:
diff --git a/lib/rubygems/request_set/lockfile/parser.rb b/lib/rubygems/request_set/lockfile/parser.rb
index 18aaadf3bb..ebea940188 100644
--- a/lib/rubygems/request_set/lockfile/parser.rb
+++ b/lib/rubygems/request_set/lockfile/parser.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 class Gem::RequestSet::Lockfile::Parser
   ###
   # Parses lockfiles
@@ -325,15 +325,24 @@ class Gem::RequestSet::Lockfile::Parser
     @tokens.peek
   end
 
-  def pinned_requirement name # :nodoc:
-    spec = @set.sets.select { |set|
-      Gem::Resolver::GitSet    === set or
-        Gem::Resolver::VendorSet === set
-    }.map { |set|
-      set.specs[name]
-    }.compact.first
+  if [].respond_to? :flat_map
+    def pinned_requirement name # :nodoc:
+      requirement = Gem::Dependency.new name
+      specification = @set.sets.flat_map { |set|
+        set.find_all(requirement)
+      }.compact.first
 
-    spec.version
+      specification && specification.version
+    end
+  else # FIXME: remove when 1.8 is dropped
+    def pinned_requirement name # :nodoc:
+      requirement = Gem::Dependency.new name
+      specification = @set.sets.map { |set|
+        set.find_all(requirement)
+      }.flatten(1).compact.first
+
+      specification && specification.version
+    end
   end
 
   ##
@@ -343,4 +352,3 @@ class Gem::RequestSet::Lockfile::Parser
     @tokens.unshift token
   end
 end
-
diff --git a/lib/rubygems/request_set/lockfile/tokenizer.rb b/lib/rubygems/request_set/lockfile/tokenizer.rb
index d68645d235..c9f1fac75b 100644
--- a/lib/rubygems/request_set/lockfile/tokenizer.rb
+++ b/lib/rubygems/request_set/lockfile/tokenizer.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'strscan'
 require 'rubygems/request_set/lockfile/parser'
 
diff --git a/lib/rubygems/requirement.rb b/lib/rubygems/requirement.rb
index a33f67dafb..32dc769055 100644
--- a/lib/rubygems/requirement.rb
+++ b/lib/rubygems/requirement.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require "rubygems/version"
 require "rubygems/deprecate"
 
diff --git a/lib/rubygems/resolver.rb b/lib/rubygems/resolver.rb
index 92dcab8e42..3a406d0444 100644
--- a/lib/rubygems/resolver.rb
+++ b/lib/rubygems/resolver.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/dependency'
 require 'rubygems/exceptions'
 require 'rubygems/util'
@@ -279,6 +279,7 @@ require 'rubygems/resolver/index_set'
 require 'rubygems/resolver/installer_set'
 require 'rubygems/resolver/lock_set'
 require 'rubygems/resolver/vendor_set'
+require 'rubygems/resolver/source_set'
 
 require 'rubygems/resolver/specification'
 require 'rubygems/resolver/spec_specification'
diff --git a/lib/rubygems/resolver/activation_request.rb b/lib/rubygems/resolver/activation_request.rb
index 2dd540cda0..135d75d6bc 100644
--- a/lib/rubygems/resolver/activation_request.rb
+++ b/lib/rubygems/resolver/activation_request.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Specifies a Specification object that should be activated.  Also contains a
 # dependency that was used to introduce this activation.
@@ -50,15 +50,27 @@ class Gem::Resolver::ActivationRequest
   # Downloads a gem at +path+ and returns the file path.
 
   def download path
-    if @spec.respond_to? :source
+    Gem.ensure_gem_subdirectories path
+
+    if @spec.respond_to? :sources
+      exception = nil
+      path = @spec.sources.find{ |source|
+        begin
+          source.download full_spec, path
+        rescue exception
+        end
+      }
+      return path      if path
+      raise  exception if exception
+
+    elsif @spec.respond_to? :source
       source = @spec.source
+      source.download full_spec, path
+
     else
       source = Gem.sources.first
+      source.download full_spec, path
     end
-
-    Gem.ensure_gem_subdirectories path
-
-    source.download full_spec, path
   end
 
   ##
diff --git a/lib/rubygems/resolver/api_set.rb b/lib/rubygems/resolver/api_set.rb
index 611c74ad10..ee3046af63 100644
--- a/lib/rubygems/resolver/api_set.rb
+++ b/lib/rubygems/resolver/api_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The global rubygems pool, available via the rubygems.org API.
 # Returns instances of APISpecification.
diff --git a/lib/rubygems/resolver/api_specification.rb b/lib/rubygems/resolver/api_specification.rb
index e7ba38d614..1e22dd0b6f 100644
--- a/lib/rubygems/resolver/api_specification.rb
+++ b/lib/rubygems/resolver/api_specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Represents a specification retrieved via the rubygems.org API.
 #
diff --git a/lib/rubygems/resolver/best_set.rb b/lib/rubygems/resolver/best_set.rb
index c3c756c5e3..4479535abe 100644
--- a/lib/rubygems/resolver/best_set.rb
+++ b/lib/rubygems/resolver/best_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The BestSet chooses the best available method to query a remote index.
 #
diff --git a/lib/rubygems/resolver/composed_set.rb b/lib/rubygems/resolver/composed_set.rb
index 66d927be2a..0b65942dca 100644
--- a/lib/rubygems/resolver/composed_set.rb
+++ b/lib/rubygems/resolver/composed_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A ComposedSet allows multiple sets to be queried like a single set.
 #
diff --git a/lib/rubygems/resolver/conflict.rb b/lib/rubygems/resolver/conflict.rb
index 101923eb74..7997f92950 100644
--- a/lib/rubygems/resolver/conflict.rb
+++ b/lib/rubygems/resolver/conflict.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Used internally to indicate that a dependency conflicted
 # with a spec that would be activated.
diff --git a/lib/rubygems/resolver/current_set.rb b/lib/rubygems/resolver/current_set.rb
index f8cec599de..265c639f15 100644
--- a/lib/rubygems/resolver/current_set.rb
+++ b/lib/rubygems/resolver/current_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A set which represents the installed gems. Respects
 # all the normal settings that control where to look
diff --git a/lib/rubygems/resolver/dependency_request.rb b/lib/rubygems/resolver/dependency_request.rb
index ded554a85a..c2918911cd 100644
--- a/lib/rubygems/resolver/dependency_request.rb
+++ b/lib/rubygems/resolver/dependency_request.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Used Internally. Wraps a Dependency object to also track which spec
 # contained the Dependency.
diff --git a/lib/rubygems/resolver/git_set.rb b/lib/rubygems/resolver/git_set.rb
index 2b5aae64c6..723a202d7a 100644
--- a/lib/rubygems/resolver/git_set.rb
+++ b/lib/rubygems/resolver/git_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A GitSet represents gems that are sourced from git repositories.
 #
diff --git a/lib/rubygems/resolver/git_specification.rb b/lib/rubygems/resolver/git_specification.rb
index 507f346812..2448797d3f 100644
--- a/lib/rubygems/resolver/git_specification.rb
+++ b/lib/rubygems/resolver/git_specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A GitSpecification represents a gem that is sourced from a git repository
 # and is being loaded through a gem dependencies file through the +git:+
diff --git a/lib/rubygems/resolver/index_set.rb b/lib/rubygems/resolver/index_set.rb
index e7cd989095..2450f14b4f 100644
--- a/lib/rubygems/resolver/index_set.rb
+++ b/lib/rubygems/resolver/index_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The global rubygems pool represented via the traditional
 # source index.
diff --git a/lib/rubygems/resolver/index_specification.rb b/lib/rubygems/resolver/index_specification.rb
index 632a8a2d89..4340f46943 100644
--- a/lib/rubygems/resolver/index_specification.rb
+++ b/lib/rubygems/resolver/index_specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Represents a possible Specification object returned from IndexSet.  Used to
 # delay needed to download full Specification objects when only the +name+
diff --git a/lib/rubygems/resolver/installed_specification.rb b/lib/rubygems/resolver/installed_specification.rb
index 06da6af3db..d9c6a5e5cf 100644
--- a/lib/rubygems/resolver/installed_specification.rb
+++ b/lib/rubygems/resolver/installed_specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # An InstalledSpecification represents a gem that is already installed
 # locally.
diff --git a/lib/rubygems/resolver/installer_set.rb b/lib/rubygems/resolver/installer_set.rb
index d840b71711..1ed02e6f9f 100644
--- a/lib/rubygems/resolver/installer_set.rb
+++ b/lib/rubygems/resolver/installer_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A set of gems for installation sourced from remote sources and local .gem
 # files
diff --git a/lib/rubygems/resolver/local_specification.rb b/lib/rubygems/resolver/local_specification.rb
index 76192e4c0b..1d9d22f0ac 100644
--- a/lib/rubygems/resolver/local_specification.rb
+++ b/lib/rubygems/resolver/local_specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A LocalSpecification comes from a .gem file on the local filesystem.
 
diff --git a/lib/rubygems/resolver/lock_set.rb b/lib/rubygems/resolver/lock_set.rb
index fb581a1508..7fddc93e1c 100644
--- a/lib/rubygems/resolver/lock_set.rb
+++ b/lib/rubygems/resolver/lock_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A set of gems from a gem dependencies lockfile.
 
@@ -28,11 +28,9 @@ class Gem::Resolver::LockSet < Gem::Resolver::Set
 
   def add name, version, platform # :nodoc:
     version = Gem::Version.new version
-
-    specs = @sources.map do |source|
-      Gem::Resolver::LockSpecification.new self, name, version, source,
-                                           platform
-    end
+    specs = [
+      Gem::Resolver::LockSpecification.new(self, name, version, @sources, platform)
+    ]
 
     @specs.concat specs
 
diff --git a/lib/rubygems/resolver/lock_specification.rb b/lib/rubygems/resolver/lock_specification.rb
index 0226878752..f485675673 100644
--- a/lib/rubygems/resolver/lock_specification.rb
+++ b/lib/rubygems/resolver/lock_specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The LockSpecification comes from a lockfile (Gem::RequestSet::Lockfile).
 #
@@ -7,13 +7,16 @@
 
 class Gem::Resolver::LockSpecification < Gem::Resolver::Specification
 
-  def initialize set, name, version, source, platform
+  attr_reader :sources
+
+  def initialize set, name, version, sources, platform
     super()
 
     @name     = name
     @platform = platform
     @set      = set
-    @source   = source
+    @source   = sources.first
+    @sources  = sources
     @version  = version
 
     @dependencies = []
diff --git a/lib/rubygems/resolver/molinillo.rb b/lib/rubygems/resolver/molinillo.rb
index 019536dc9b..2357f41bee 100644
--- a/lib/rubygems/resolver/molinillo.rb
+++ b/lib/rubygems/resolver/molinillo.rb
@@ -1,2 +1,2 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/resolver/molinillo/lib/molinillo'
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo.rb b/lib/rubygems/resolver/molinillo/lib/molinillo.rb
index 34dc7787dc..0ae4b6a912 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo.rb
@@ -1,6 +1,10 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/resolver/molinillo/lib/molinillo/gem_metadata'
 require 'rubygems/resolver/molinillo/lib/molinillo/errors'
 require 'rubygems/resolver/molinillo/lib/molinillo/resolver'
 require 'rubygems/resolver/molinillo/lib/molinillo/modules/ui'
 require 'rubygems/resolver/molinillo/lib/molinillo/modules/specification_provider'
+
+# Gem::Resolver::Molinillo is a generic dependency resolution algorithm.
+module Gem::Resolver::Molinillo
+end
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb
index c3a1d5a2ef..deb4659448 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'set'
 require 'tsort'
 
@@ -15,8 +15,10 @@ module Gem::Resolver::Molinillo
 
     include TSort
 
+    # @visibility private
     alias_method :tsort_each_node, :each
 
+    # @visibility private
     def tsort_each_child(vertex, &block)
       vertex.successors.each(&block)
     end
@@ -42,12 +44,14 @@ module Gem::Resolver::Molinillo
     #   by {Vertex#name}
     attr_reader :vertices
 
+    # Initializes an empty dependency graph
     def initialize
       @vertices = {}
     end
 
     # Initializes a copy of a {DependencyGraph}, ensuring that all {#vertices}
     # are properly copied.
+    # @param [DependencyGraph] other the graph to copy.
     def initialize_copy(other)
       super
       @vertices = {}
@@ -101,6 +105,7 @@ module Gem::Resolver::Molinillo
       vertex
     end
 
+    # Adds a vertex with the given name, or updates the existing one.
     # @param [String] name
     # @param [Object] payload
     # @return [Vertex] the vertex that was added to `self`
@@ -151,6 +156,8 @@ module Gem::Resolver::Molinillo
 
     private
 
+    # Adds a new {Edge} to the dependency graph without checking for
+    # circularity.
     def add_edge_no_circular(origin, destination, requirement)
       edge = Edge.new(origin, destination, requirement)
       origin.outgoing_edges << edge
@@ -175,6 +182,7 @@ module Gem::Resolver::Molinillo
       attr_accessor :root
       alias_method :root?, :root
 
+      # Initializes a vertex with the given name and payload.
       # @param [String] name see {#name}
       # @param [Object] payload see {#payload}
       def initialize(name, payload)
@@ -241,6 +249,7 @@ module Gem::Resolver::Molinillo
           successors.to_set == other.successors.to_set
       end
 
+      # @param  [Vertex] other the other vertex to compare to
       # @return [Boolean] whether the two vertices are equal, determined
       #   solely by {#name} and {#payload} equality
       def shallow_eql?(other)
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/errors.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/errors.rb
index 074ee9dd7d..3fad948392 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/errors.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/errors.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Gem::Resolver::Molinillo
   # An error that occurred during the resolution process
   class ResolverError < StandardError; end
@@ -12,6 +12,7 @@ module Gem::Resolver::Molinillo
     # @return [Array<Object>] the specifications that depended upon {#dependency}
     attr_accessor :required_by
 
+    # Initializes a new error with the given missing dependency.
     # @param [Object] dependency @see {#dependency}
     # @param [Array<Object>] required_by @see {#required_by}
     def initialize(dependency, required_by = [])
@@ -20,6 +21,8 @@ module Gem::Resolver::Molinillo
       super()
     end
 
+    # The error message for the missing dependency, including the specifications
+    # that had this dependency.
     def message
       sources = required_by.map { |r| "`#{r}`" }.join(' and ')
       message = "Unable to find a specification for `#{dependency}`"
@@ -37,6 +40,7 @@ module Gem::Resolver::Molinillo
     # [Set<Object>] the dependencies responsible for causing the error
     attr_reader :dependencies
 
+    # Initializes a new error with the given circular vertices.
     # @param [Array<DependencyGraph::Vertex>] nodes the nodes in the dependency
     #   that caused the error
     def initialize(nodes)
@@ -51,6 +55,7 @@ module Gem::Resolver::Molinillo
     #   resolution to fail
     attr_reader :conflicts
 
+    # Initializes a new error with the given version conflicts.
     # @param [{String => Resolution::Conflict}] conflicts see {#conflicts}
     def initialize(conflicts)
       pairs = []
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/gem_metadata.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/gem_metadata.rb
index 8140c57a58..79cae2c697 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/gem_metadata.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/gem_metadata.rb
@@ -1,4 +1,5 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Gem::Resolver::Molinillo
-  VERSION = '0.4.0'
+  # The version of Gem::Resolver::Molinillo.
+  VERSION = '0.4.1'.freeze
 end
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/modules/specification_provider.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/modules/specification_provider.rb
index 10c655ac32..916345b12a 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/modules/specification_provider.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/modules/specification_provider.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Gem::Resolver::Molinillo
   # Provides information about specifcations and dependencies to the resolver,
   # allowing the {Resolver} class to remain generic while still providing power
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/modules/ui.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/modules/ui.rb
index 100b694ebc..348ace286a 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/modules/ui.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/modules/ui.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Gem::Resolver::Molinillo
   # Conveys information about the resolution process to a user.
   module UI
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb
index 5a0eb36849..0f822f0b82 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Gem::Resolver::Molinillo
   class Resolver
     # A specific resolution from a given {Resolver}
@@ -39,6 +39,7 @@ module Gem::Resolver::Molinillo
       # @return [Array] the dependencies that were explicitly required
       attr_reader :original_requested
 
+      # Initializes a new resolution.
       # @param [SpecificationProvider] specification_provider
       #   see {#specification_provider}
       # @param [UI] resolver_ui see {#resolver_ui}
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/resolver.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/resolver.rb
index a92b3273ab..5c59a45c3d 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/resolver.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/resolver.rb
@@ -1,10 +1,10 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/resolver/molinillo/lib/molinillo/dependency_graph'
 
 module Gem::Resolver::Molinillo
   # This class encapsulates a dependency resolver.
   # The resolver is responsible for determining which set of dependencies to
-  # activate, with feedback from the the {#specification_provider}
+  # activate, with feedback from the {#specification_provider}
   #
   #
   class Resolver
@@ -18,6 +18,7 @@ module Gem::Resolver::Molinillo
     #   during the resolution process
     attr_reader :resolver_ui
 
+    # Initializes a new resolver.
     # @param  [SpecificationProvider] specification_provider
     #   see {#specification_provider}
     # @param  [UI] resolver_ui
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/state.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/state.rb
index 7bc9d98927..ac25538a5a 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/state.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/state.rb
@@ -1,13 +1,13 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Gem::Resolver::Molinillo
   # A state that a {Resolution} can be in
-  # @attr [String] name
-  # @attr [Array<Object>] requirements
-  # @attr [DependencyGraph] activated
-  # @attr [Object] requirement
-  # @attr [Object] possibility
-  # @attr [Integer] depth
-  # @attr [Set<Object>] conflicts
+  # @attr [String] name the name of the current requirement
+  # @attr [Array<Object>] requirements currently unsatisfied requirements
+  # @attr [DependencyGraph] activated the graph of activated dependencies
+  # @attr [Object] requirement the current requirement
+  # @attr [Object] possibilities the possibilities to satisfy the current requirement
+  # @attr [Integer] depth the depth of the resolution
+  # @attr [Set<Object>] conflicts unresolved conflicts
   ResolutionState = Struct.new(
     :name,
     :requirements,
diff --git a/lib/rubygems/resolver/requirement_list.rb b/lib/rubygems/resolver/requirement_list.rb
index 32f2ac5a99..2768c80170 100644
--- a/lib/rubygems/resolver/requirement_list.rb
+++ b/lib/rubygems/resolver/requirement_list.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The RequirementList is used to hold the requirements being considered
 # while resolving a set of gems.
diff --git a/lib/rubygems/resolver/set.rb b/lib/rubygems/resolver/set.rb
index e2253abf3a..cc12633d46 100644
--- a/lib/rubygems/resolver/set.rb
+++ b/lib/rubygems/resolver/set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Resolver sets are used to look up specifications (and their
 # dependencies) used in resolution.  This set is abstract.
diff --git a/lib/rubygems/resolver/source_set.rb b/lib/rubygems/resolver/source_set.rb
new file mode 100644
index 0000000000..66f5963e54
--- /dev/null
+++ b/lib/rubygems/resolver/source_set.rb
@@ -0,0 +1,48 @@
+##
+# The SourceSet chooses the best available method to query a remote index.
+#
+# Kind off like BestSet but filters the sources for gems
+
+class Gem::Resolver::SourceSet < Gem::Resolver::Set
+
+  ##
+  # Creates a SourceSet for the given +sources+ or Gem::sources if none are
+  # specified.  +sources+ must be a Gem::SourceList.
+
+  def initialize
+    super()
+
+    @links = {}
+    @sets  = {}
+  end
+
+  def find_all req # :nodoc:
+    if set = get_set(req.dependency.name)
+      set.find_all req
+    else
+      []
+    end
+  end
+
+  # potentially no-op
+  def prefetch reqs # :nodoc:
+    reqs.each do |req|
+      if set = get_set(req.dependency.name)
+        set.prefetch reqs
+      end
+    end
+  end
+
+  def add_source_gem name, source
+    @links[name] = source
+  end
+
+private
+
+  def get_set(name)
+    link = @links[name]
+    @sets[link] ||= Gem::Source.new(link).dependency_resolver_set if link
+  end
+
+end
+
diff --git a/lib/rubygems/resolver/spec_specification.rb b/lib/rubygems/resolver/spec_specification.rb
index 00a0533bb5..35ee8cc247 100644
--- a/lib/rubygems/resolver/spec_specification.rb
+++ b/lib/rubygems/resolver/spec_specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The Resolver::SpecSpecification contains common functionality for
 # Resolver specifications that are backed by a Gem::Specification.
diff --git a/lib/rubygems/resolver/specification.rb b/lib/rubygems/resolver/specification.rb
index 5833320660..44989d39ae 100644
--- a/lib/rubygems/resolver/specification.rb
+++ b/lib/rubygems/resolver/specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A Resolver::Specification contains a subset of the information
 # contained in a Gem::Specification.  Only the information necessary for
diff --git a/lib/rubygems/resolver/stats.rb b/lib/rubygems/resolver/stats.rb
index 4de766f2e1..3b95efebf7 100644
--- a/lib/rubygems/resolver/stats.rb
+++ b/lib/rubygems/resolver/stats.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 class Gem::Resolver::Stats
   def initialize
     @max_depth = 0
diff --git a/lib/rubygems/resolver/vendor_set.rb b/lib/rubygems/resolver/vendor_set.rb
index a006220ffe..f30ce534af 100644
--- a/lib/rubygems/resolver/vendor_set.rb
+++ b/lib/rubygems/resolver/vendor_set.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A VendorSet represents gems that have been unpacked into a specific
 # directory that contains a gemspec.
diff --git a/lib/rubygems/resolver/vendor_specification.rb b/lib/rubygems/resolver/vendor_specification.rb
index ecf8e74def..c624f3e834 100644
--- a/lib/rubygems/resolver/vendor_specification.rb
+++ b/lib/rubygems/resolver/vendor_specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A VendorSpecification represents a gem that has been unpacked into a project
 # and is being loaded through a gem dependencies file through the +path:+
diff --git a/lib/rubygems/security.rb b/lib/rubygems/security.rb
index 941462d7bd..119d6d56f7 100644
--- a/lib/rubygems/security.rb
+++ b/lib/rubygems/security.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/security/policies.rb b/lib/rubygems/security/policies.rb
index 05c6bbdb2a..f16c46306a 100644
--- a/lib/rubygems/security/policies.rb
+++ b/lib/rubygems/security/policies.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Gem::Security
 
   ##
diff --git a/lib/rubygems/security/policy.rb b/lib/rubygems/security/policy.rb
index 0e13497b9d..f43e6c8c96 100644
--- a/lib/rubygems/security/policy.rb
+++ b/lib/rubygems/security/policy.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/user_interaction'
 
 ##
@@ -158,7 +158,7 @@ class Gem::Security::Policy
     path = Gem::Security.trust_dir.cert_path root
 
     unless File.exist? path then
-      message = "root cert #{root.subject} is not trusted"
+      message = "root cert #{root.subject} is not trusted".dup
 
       message << " (root of signing cert #{chain.last.subject})" if
         chain.length > 1
@@ -293,4 +293,3 @@ class Gem::Security::Policy
   alias to_s name # :nodoc:
 
 end
-
diff --git a/lib/rubygems/security/signer.rb b/lib/rubygems/security/signer.rb
index a6d0161edc..1c9d9b7d3b 100644
--- a/lib/rubygems/security/signer.rb
+++ b/lib/rubygems/security/signer.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Basic OpenSSL-based package signing class.
 
diff --git a/lib/rubygems/security/trust_dir.rb b/lib/rubygems/security/trust_dir.rb
index a032debf6e..bf44975cc6 100644
--- a/lib/rubygems/security/trust_dir.rb
+++ b/lib/rubygems/security/trust_dir.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The TrustDir manages the trusted certificates for gem signature
 # verification.
diff --git a/lib/rubygems/server.rb b/lib/rubygems/server.rb
index d83a928571..8d6a96b1c2 100644
--- a/lib/rubygems/server.rb
+++ b/lib/rubygems/server.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'webrick'
 require 'zlib'
 require 'erb'
diff --git a/lib/rubygems/source.rb b/lib/rubygems/source.rb
index 7a58a441d2..85f5268fa3 100644
--- a/lib/rubygems/source.rb
+++ b/lib/rubygems/source.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'uri'
 require 'fileutils'
 
diff --git a/lib/rubygems/source/git.rb b/lib/rubygems/source/git.rb
index 7096ebe617..0900da0cbc 100644
--- a/lib/rubygems/source/git.rb
+++ b/lib/rubygems/source/git.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'digest'
 require 'rubygems/util'
 
diff --git a/lib/rubygems/source/installed.rb b/lib/rubygems/source/installed.rb
index 3327010768..300491e467 100644
--- a/lib/rubygems/source/installed.rb
+++ b/lib/rubygems/source/installed.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Represents an installed gem.  This is used for dependency resolution.
 
diff --git a/lib/rubygems/source/local.rb b/lib/rubygems/source/local.rb
index a320ff1c66..3227fb61b0 100644
--- a/lib/rubygems/source/local.rb
+++ b/lib/rubygems/source/local.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The local source finds gems in the current directory for fulfilling
 # dependencies.
diff --git a/lib/rubygems/source/lock.rb b/lib/rubygems/source/lock.rb
index 98fef5a4d1..86b16e964c 100644
--- a/lib/rubygems/source/lock.rb
+++ b/lib/rubygems/source/lock.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A Lock source wraps an installed gem's source and sorts before other sources
 # during dependency resolution.  This allows RubyGems to prefer gems from
diff --git a/lib/rubygems/source/specific_file.rb b/lib/rubygems/source/specific_file.rb
index 790e424033..459c803e1a 100644
--- a/lib/rubygems/source/specific_file.rb
+++ b/lib/rubygems/source/specific_file.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # A source representing a single .gem file.  This is used for installation of
 # local gems.
diff --git a/lib/rubygems/source/vendor.rb b/lib/rubygems/source/vendor.rb
index 057d54ebea..e1b3698607 100644
--- a/lib/rubygems/source/vendor.rb
+++ b/lib/rubygems/source/vendor.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # This represents a vendored source that is similar to an installed gem.
 
diff --git a/lib/rubygems/source_list.rb b/lib/rubygems/source_list.rb
index add82f2327..942d657963 100644
--- a/lib/rubygems/source_list.rb
+++ b/lib/rubygems/source_list.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/source'
 
 ##
@@ -10,7 +10,7 @@ require 'rubygems/source'
 # Or by adding them:
 #
 #   sources = Gem::SourceList.new
-#   sources.add 'https://rubygems.example'
+#   sources << 'https://rubygems.example'
 #
 # The most common way to get a SourceList is Gem.sources.
 
diff --git a/lib/rubygems/source_local.rb b/lib/rubygems/source_local.rb
index d56b697718..07cb9e6e8f 100644
--- a/lib/rubygems/source_local.rb
+++ b/lib/rubygems/source_local.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/source'
 require 'rubygems/source_local'
 
diff --git a/lib/rubygems/source_specific_file.rb b/lib/rubygems/source_specific_file.rb
index 2ae5792781..d42e6e7440 100644
--- a/lib/rubygems/source_specific_file.rb
+++ b/lib/rubygems/source_specific_file.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/source/specific_file'
 
 # TODO warn upon require, this file is deprecated.
diff --git a/lib/rubygems/spec_fetcher.rb b/lib/rubygems/spec_fetcher.rb
index dbeecad243..755d4be1eb 100644
--- a/lib/rubygems/spec_fetcher.rb
+++ b/lib/rubygems/spec_fetcher.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems/remote_fetcher'
 require 'rubygems/user_interaction'
 require 'rubygems/errors'
diff --git a/lib/rubygems/specification.rb b/lib/rubygems/specification.rb
index ddba38da84..8e2557cdb2 100644
--- a/lib/rubygems/specification.rb
+++ b/lib/rubygems/specification.rb
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -1192,6 +1192,7 @@ class Gem::Specification < Gem::BasicSpecification
   def self.normalize_yaml_input(input)
     result = input.respond_to?(:read) ? input.read : input
     result = "--- " + result unless result =~ /\A--- /
+    result = result.dup
     result.gsub!(/ !!null \n/, " \n")
     # date: 2011-04-26 00:00:00.000000000Z
     # date: 2011-04-26 00:00:00.000000000 Z
@@ -2334,7 +2335,7 @@ class Gem::Specification < Gem::BasicSpecification
 
   def ruby_code(obj)
     case obj
-    when String            then obj.dump
+    when String            then obj.dump + ".freeze"
     when Array             then '[' + obj.map { |x| ruby_code x }.join(", ") + ']'
     when Hash              then
       seg = obj.keys.sort.map { |k| "#{k.to_s.dump} => #{obj[k].to_s.dump}" }
@@ -2524,14 +2525,14 @@ class Gem::Specification < Gem::BasicSpecification
       dependencies.each do |dep|
         req = dep.requirements_list.inspect
         dep.instance_variable_set :@type, :runtime if dep.type.nil? # HACK
-        result << "      s.add_#{dep.type}_dependency(%q<#{dep.name}>, #{req})"
+        result << "      s.add_#{dep.type}_dependency(%q<#{dep.name}>.freeze, #{req})"
       end
 
       result << "    else"
 
       dependencies.each do |dep|
         version_reqs_param = dep.requirements_list.inspect
-        result << "      s.add_dependency(%q<#{dep.name}>, #{version_reqs_param})"
+        result << "      s.add_dependency(%q<#{dep.name}>.freeze, #{version_reqs_param})"
       end
 
       result << '    end'
@@ -2539,7 +2540,7 @@ class Gem::Specification < Gem::BasicSpecification
       result << "  else"
       dependencies.each do |dep|
         version_reqs_param = dep.requirements_list.inspect
-        result << "    s.add_dependency(%q<#{dep.name}>, #{version_reqs_param})"
+        result << "    s.add_dependency(%q<#{dep.name}>.freeze, #{version_reqs_param})"
       end
       result << "  end"
     end
@@ -2761,10 +2762,13 @@ class Gem::Specification < Gem::BasicSpecification
       end
 
       if !Gem::Licenses.match?(license)
-        warning <<-warning
-WARNING: license value '#{license}' is invalid.  Use a license identifier from
+        suggestions = Gem::Licenses.suggestions(license)
+        message = <<-warning
+license value '#{license}' is invalid.  Use a license identifier from
 http://spdx.org/licenses or '#{Gem::Licenses::NONSTANDARD}' for a nonstandard license.
         warning
+        message += "Did you mean #{suggestions.map { |s| "'#{s}'"}.join(', ')}?\n" unless suggestions.nil?
+        warning(message)
       end
     }
 
diff --git a/lib/rubygems/stub_specification.rb b/lib/rubygems/stub_specification.rb
index 98ec7ce070..61df5a2262 100644
--- a/lib/rubygems/stub_specification.rb
+++ b/lib/rubygems/stub_specification.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # Gem::StubSpecification reads the stub: line from the gemspec.  This prevents
 # us having to eval the entire gemspec in order to find out certain
diff --git a/lib/rubygems/syck_hack.rb b/lib/rubygems/syck_hack.rb
index 0f49793ea1..051483eac8 100644
--- a/lib/rubygems/syck_hack.rb
+++ b/lib/rubygems/syck_hack.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # :stopdoc:
 
 # Hack to handle syck's DefaultKey bug
diff --git a/lib/rubygems/test_case.rb b/lib/rubygems/test_case.rb
index c31f29403e..43c4667822 100644
--- a/lib/rubygems/test_case.rb
+++ b/lib/rubygems/test_case.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # TODO: $SAFE = 1
 
 begin
@@ -553,7 +553,7 @@ class Gem::TestCase < MiniTest::Unit::TestCase
   # Enables pretty-print for all tests
 
   def mu_pp(obj)
-    s = ''
+    s = String.new
     s = PP.pp obj, s
     s = s.force_encoding(Encoding.default_external) if defined? Encoding
     s.chomp
@@ -1318,12 +1318,22 @@ Also, a list:
   def vendor_gem name = 'a', version = 1
     directory = File.join 'vendor', name
 
+    FileUtils.mkdir_p directory
+
+    save_gemspec name, version, directory
+  end
+
+  ##
+  # create_gemspec creates gem specification in given +direcotry+ or '.'
+  # for the given +name+ and +version+.
+  #
+  # Yields the +specification+ to the block, if given
+
+  def save_gemspec name = 'a', version = 1, directory = '.'
     vendor_spec = Gem::Specification.new name, version do |specification|
       yield specification if block_given?
     end
 
-    FileUtils.mkdir_p directory
-
     open File.join(directory, "#{name}.gemspec"), 'w' do |io|
       io.write vendor_spec.to_ruby
     end
@@ -1494,3 +1504,4 @@ tmpdirs << (ENV['GEM_PATH'] = Dir.mktmpdir("path"))
 pid = $$
 END {tmpdirs.each {|dir| Dir.rmdir(dir)} if $$ == pid}
 Gem.clear_paths
+
diff --git a/lib/rubygems/test_utilities.rb b/lib/rubygems/test_utilities.rb
index bb633eb3cc..686916ea02 100644
--- a/lib/rubygems/test_utilities.rb
+++ b/lib/rubygems/test_utilities.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'tempfile'
 require 'rubygems'
 require 'rubygems/remote_fetcher'
diff --git a/lib/rubygems/text.rb b/lib/rubygems/text.rb
index 470874621b..732f1b99f2 100644
--- a/lib/rubygems/text.rb
+++ b/lib/rubygems/text.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'rubygems'
 
 ##
@@ -71,4 +71,3 @@ module Gem::Text
     return x
   end
 end
-
diff --git a/lib/rubygems/uninstaller.rb b/lib/rubygems/uninstaller.rb
index b54eeba585..89f47a45fe 100644
--- a/lib/rubygems/uninstaller.rb
+++ b/lib/rubygems/uninstaller.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/uri_formatter.rb b/lib/rubygems/uri_formatter.rb
index bf0fc287a4..bb128e4ef9 100644
--- a/lib/rubygems/uri_formatter.rb
+++ b/lib/rubygems/uri_formatter.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'cgi'
 require 'uri'
 
diff --git a/lib/rubygems/user_interaction.rb b/lib/rubygems/user_interaction.rb
index 69eb26df5a..6c8534dd55 100644
--- a/lib/rubygems/user_interaction.rb
+++ b/lib/rubygems/user_interaction.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/util.rb b/lib/rubygems/util.rb
index 76d8ad4bc1..ead2babc1f 100644
--- a/lib/rubygems/util.rb
+++ b/lib/rubygems/util.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # This module contains various utility methods as module methods.
 
@@ -25,7 +25,7 @@ module Gem::Util
   def self.gzip(data)
     require 'zlib'
     require 'stringio'
-    zipped = StringIO.new('','w')
+    zipped = StringIO.new(String.new, 'w')
     zipped.set_encoding Encoding::BINARY if Object.const_defined? :Encoding
 
     Zlib::GzipWriter.wrap zipped do |io| io.write data end
diff --git a/lib/rubygems/util/licenses.rb b/lib/rubygems/util/licenses.rb
index 08ebd925f7..f4a99af39e 100644
--- a/lib/rubygems/util/licenses.rb
+++ b/lib/rubygems/util/licenses.rb
@@ -1,5 +1,9 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
+require 'rubygems/text'
+
 class Gem::Licenses
+  extend Gem::Text
+
   NONSTANDARD = 'Nonstandard'.freeze
 
   # Software Package Data Exchange (SPDX) standard open-source software
@@ -327,4 +331,13 @@ class Gem::Licenses
   def self.match?(license)
     !REGEXP.match(license).nil?
   end
+
+  def self.suggestions(license)
+    by_distance = IDENTIFIERS.group_by do |identifier|
+      levenshtein_distance(identifier, license)
+    end
+    lowest = by_distance.keys.min
+    return unless lowest < license.size
+    by_distance[lowest]
+  end
 end
diff --git a/lib/rubygems/util/list.rb b/lib/rubygems/util/list.rb
index 83dc8497c4..9c25f6b6dc 100644
--- a/lib/rubygems/util/list.rb
+++ b/lib/rubygems/util/list.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Gem
   class List
     include Enumerable
diff --git a/lib/rubygems/validator.rb b/lib/rubygems/validator.rb
index 8a13e9911b..83448229bb 100644
--- a/lib/rubygems/validator.rb
+++ b/lib/rubygems/validator.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/version.rb b/lib/rubygems/version.rb
index 8e37baa348..54da49e8e8 100644
--- a/lib/rubygems/version.rb
+++ b/lib/rubygems/version.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 ##
 # The Version class processes string versions into comparable
 # values. A version string should normally be a series of numbers
@@ -282,7 +282,10 @@ class Gem::Version
   # A version is considered a prerelease if it contains a letter.
 
   def prerelease?
-    @prerelease ||= !!(@version =~ /[a-zA-Z]/)
+    unless instance_variable_defined? :@prerelease
+      @prerelease = !!(@version =~ /[a-zA-Z]/)
+    end
+    @prerelease
   end
 
   def pretty_print q # :nodoc:
diff --git a/lib/rubygems/version_option.rb b/lib/rubygems/version_option.rb
index a31cb14db4..3209d95f0f 100644
--- a/lib/rubygems/version_option.rb
+++ b/lib/rubygems/version_option.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
-- 
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