Merge rubygems-2.6.12 from rubygems/rubygems.

* Details of changes:
    0090800402/History.txt (L3)

  * I kept ko1's commmit related thread issue. It's not merged 2.6 branch on rubygems.
    1721dfa0ea

  * I removed test_realworld_default_gem from rubygems-2.6.12. It fails on
    Ruby trunk. Because it's differences of test suite and environment.
    https://github.com/rubygems/rubygems/pull/1899

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58530 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/rubygems/commands/open_command.rb

@@ -72,7 +72,7 @@ class Gem::Commands::OpenCommand < Gem::Command
   end
 
   def spec_for name
-    spec = Gem::Specification.find_all_by_name(name, @version).last
+    spec = Gem::Specification.find_all_by_name(name, @version).first
 
     return spec if spec
 

lib/rubygems/commands/query_command.rb

@@ -86,7 +86,7 @@ is too hard to use.
       name = Array(options[:name])
     else
       args = options[:args].to_a
-      name = options[:exact] ? args : args.map{|arg| /#{arg}/i }
+      name = options[:exact] ? args.map{|arg| /\A#{Regexp.escape(arg)}\Z/ } : args.map{|arg| /#{arg}/i }
     end
 
     prerelease = options[:prerelease]

lib/rubygems/commands/sources_command.rb

@@ -44,7 +44,7 @@ class Gem::Commands::SourcesCommand < Gem::Command
     source = Gem::Source.new source_uri
 
     begin
-      if Gem.sources.include? source_uri then
+      if Gem.sources.include? source then
         say "source #{source_uri} already present in the cache"
       else
         source.load_specs :released