[rubygems/rubygems] Fix parallel installer race condition

The main thread may detect that installation has finished and thus
abort, while the thread responsible for installing the spec that failed
has not yet set the error message.

In this case, the install process will abort with a misterious "empty"
exception. I can be force the issue to reproduce by applying the
following patch:

```diff
diff --git a/bundler/lib/bundler/installer/parallel_installer.rb b/bundler/lib/bundler/installer/parallel_installer.rb
index 3dee9f4664..7827a11d11 100644
--- a/bundler/lib/bundler/installer/parallel_installer.rb
+++ b/bundler/lib/bundler/installer/parallel_installer.rb
@@ -166,6 +166,7 @@ module Bundler
         spec_install.post_install_message = message unless message.nil?
       else
         spec_install.state = :failed
+        sleep 1
         spec_install.error = "#{message}\n\n#{require_tree_for_spec(spec_install.spec)}"
       end
       Plugin.hook(Plugin::Events::GEM_AFTER_INSTALL, spec_install)
@@ -183,6 +184,7 @@ module Bundler
     end

     def finished_installing?
+      sleep 0.5
       @specs.all? do |spec|
         return true if spec.failed?
         spec.installed?
diff --git a/bundler/lib/bundler/rubygems_gem_installer.rb b/bundler/lib/bundler/rubygems_gem_installer.rb
index 8ce33c3953..c585cd517b 100644
--- a/bundler/lib/bundler/rubygems_gem_installer.rb
+++ b/bundler/lib/bundler/rubygems_gem_installer.rb
@@ -42,6 +42,7 @@ module Bundler
       return true unless source = @package.instance_variable_get(:@gem)
       return true unless source.respond_to?(:with_read_io)
       digest = source.with_read_io do |io|
+        raise BundlerError, "asdafss"
         digest = SharedHelpers.digest(:SHA256).new
         digest << io.read(16_384) until io.eof?
         io.rewind
```

and running `bin/rspec spec/install/gems/compact_index_spec.rb:892` will
result in

```
Run options:
  include {:locations=>{"./spec/install/gems/compact_index_spec.rb"=>[892]}}
  exclude {:jruby=>true, :readline=>false, :permissions=>false, :no_color_tty=>false, :ruby_repo=>false, :bundler=>"!= 2", :git=>"!= 2.26.2", :rubygems=>"!= 3.2.0.pre1", :realworld=>true, :sudo=>true}

Randomized with seed 59277
F

Retried examples: 0

Failures:

  1) compact index api checksum validation raises when the checksum is the wrong length
     Failure/Error: expect(err).to include("The given checksum for rack-1.0.0 (\"checksum!\") is not a valid SHA256 hexdigest nor base64digest")

       expected "" to include "The given checksum for rack-1.0.0 (\"checksum!\") is not a valid SHA256 hexdigest nor base64digest"

       Commands:
       $ /home/deivid/.rbenv/versions/2.7.1/bin/ruby -I/home/deivid/Code/rubygems/rubygems/bundler/spec -r/home/deivid/Code/rubygems/rubygems/bundler/spec/support/artifice/compact_index_wrong_gem_checksum.rb -r/home/deivid/Code/rubygems/rubygems/bundler/spec/support/hax.rb /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/bin/bundle install --verbose --retry 0
       Running `bundle install --retry 0 --verbose` with bundler 2.2.0.dev
       Found changes from the lockfile, re-resolving dependencies because the list of sources changed, the dependencies in your gemfile changed, you added a new platform to your gemfile
       HTTP GET http://localgemserver.test/versions
       HTTP 200 OK http://localgemserver.test/versions
       Fetching gem metadata from http://localgemserver.test/
       Looking up gems ["rack"]
       HTTP GET http://localgemserver.test/info/rack
       HTTP 200 OK http://localgemserver.test/info/rack
       Resolving dependencies...
       Using bundler 2.2.0.dev
       0:  bundler (2.2.0.dev) from /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/specifications/bundler-2.2.0.dev.gemspec
       Fetching rack 1.0.0
       Installing rack 1.0.0
       Bundler::InstallError:
       /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/installer/parallel_installer.rb:199:in `handle_error'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/installer/parallel_installer.rb:102:in `call'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/installer/parallel_installer.rb:78:in `call'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/installer.rb:271:in `install_in_parallel'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/installer.rb:197:in `install'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/installer.rb:92:in `block in run'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/process_lock.rb:12:in `block in lock'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/process_lock.rb:9:in `open'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/process_lock.rb:9:in `lock'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/installer.rb:73:in `run'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/installer.rb:25:in `install'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/cli/install.rb:66:in `run'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/cli.rb:261:in `block in install'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/settings.rb:121:in `temporary'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/cli.rb:260:in `install'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/vendor/thor/lib/thor.rb:399:in `dispatch'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/cli.rb:30:in `dispatch'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/vendor/thor/lib/thor/base.rb:476:in `start'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/cli.rb:24:in `start'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/exe/bundle:49:in `block in <top (required)>'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/lib/bundler/friendly_errors.rb:117:in `with_friendly_errors'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/gems/bundler-2.2.0.dev/exe/bundle:37:in `<top (required)>'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/bin/bundle:23:in `load'
         /home/deivid/Code/rubygems/rubygems/bundler/tmp/1/gems/system/bin/bundle:23:in `<main>'
       # $? => 5
     # ./spec/install/gems/compact_index_spec.rb:892:in `block (3 levels) in <top (required)>'
     # ./spec/spec_helper.rb:104:in `block (4 levels) in <top (required)>'
     # ./spec/spec_helper.rb:104:in `block (3 levels) in <top (required)>'
     # ./spec/support/helpers.rb:352:in `block in with_gem_path_as'
     # ./spec/support/helpers.rb:366:in `without_env_side_effects'
     # ./spec/support/helpers.rb:348:in `with_gem_path_as'
     # ./spec/spec_helper.rb:101:in `block (2 levels) in <top (required)>'
     # ./spec/spec_helper.rb:73:in `block (2 levels) in <top (required)>'
     # ./spec/support/rubygems_ext.rb:90:in `load'
     # ./spec/support/rubygems_ext.rb:90:in `gem_load_and_activate'
     # ./spec/support/rubygems_ext.rb:18:in `gem_load'

Finished in 3.01 seconds (files took 0.14209 seconds to load)
1 example, 1 failure

Failed examples:

rspec ./spec/install/gems/compact_index_spec.rb:886 # compact index api checksum validation raises when the checksum is the wrong length

Randomized with seed 59277
```

Without any mention to `BundlerError` and the original "asdafss" message.

Fix the issue by making sure the error message is set before the ":failed"
status.

https://github.com/rubygems/rubygems/commit/83c8feb2c4

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/bundler/installer/parallel_installer.rb b/lib/bundler/installer/parallel_installer.rb
index 3dee9f4664..ad34e4f484 100644
--- a/lib/bundler/installer/parallel_installer.rb
+++ b/lib/bundler/installer/parallel_installer.rb
@@ -165,8 +165,8 @@ module Bundler
         spec_install.state = :installed
         spec_install.post_install_message = message unless message.nil?
       else
-        spec_install.state = :failed
         spec_install.error = "#{message}\n\n#{require_tree_for_spec(spec_install.spec)}"
+        spec_install.state = :failed
       end
       Plugin.hook(Plugin::Events::GEM_AFTER_INSTALL, spec_install)
       spec_install