merges r28693, r28695 and r28703 from trunk into ruby_1_9_2.

--
* lib/rubygems/custom_require.rb, gem_prelude.rb: Load code from
  from gems properly.

* lib/rubygems.rb: Load the custom require if --disable-rubygems
  was used.

* gem_prelude.rb: Pull in rubygem's custom require
  [ruby-core:30846]

* lib/rubygems.rb: Handle always having custom require available

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_2@28786 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 25 insertions, 14 deletions

diff --git a/lib/rubygems.rb b/lib/rubygems.rb
index 51661159cc..fcb1ebd3db 100644
--- a/lib/rubygems.rb
+++ b/lib/rubygems.rb
@@ -1031,7 +1031,7 @@ end
 
 module Kernel
 
-  undef gem if respond_to? :gem # defined in gem_prelude.rb on 1.9
+  remove_method :gem if respond_to?(:gem, true) # defined in gem_prelude.rb on 1.9
 
   ##
   # Use Kernel#gem to activate a specific version of +gem_name+.
@@ -1109,14 +1109,27 @@ end
 
 require 'rubygems/config_file'
 
-Gem.remove_prelude_paths
+class << Gem
+  remove_method :try_activate if Gem.respond_to?(:try_activate, true)
+
+  def try_activate(path)
+    spec = Gem.searcher.find(path)
+    return false unless spec
+
+    Gem.activate(spec.name, "= #{spec.version}")
+    return true
+  end
+end
 
 ##
 # Enables the require hook for RubyGems.
 #
-# We remove the paths prelude added, so we need custom require to get
-# any gems now.
-require 'rubygems/custom_require'
+# if --disable-rubygems was used, then the prelude wasn't loaded, so
+# we need to load the custom_require now.
+
+if gem_disabled
+  require 'rubygems/custom_require'
+end
 
 Gem.clear_paths
 
diff --git a/lib/rubygems/custom_require.rb b/lib/rubygems/custom_require.rb
index 43b3136b60..480cb7e315 100644
--- a/lib/rubygems/custom_require.rb
+++ b/lib/rubygems/custom_require.rb
@@ -4,8 +4,6 @@
 # See LICENSE.txt for permissions.
 #++
 
-require 'rubygems'
-
 module Kernel
 
   ##
@@ -30,17 +28,17 @@ module Kernel
   def require(path) # :doc:
     gem_original_require path
   rescue LoadError => load_error
-    if load_error.message.end_with?(path) and
-       spec = Gem.searcher.find(path) then
-      Gem.activate(spec.name, "= #{spec.version}")
-      gem_original_require path
-    else
-      raise load_error
+    if load_error.message.end_with?(path)
+      if Gem.try_activate(path)
+        return gem_original_require(path)
+      end
     end
+
+    raise load_error
   end
 
   private :require
   private :gem_original_require
 
-end
+end unless Kernel.private_method_defined?(:gem_original_require)