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merge revision(s) 39533: [Backport #7991]

    * lib/rubygems/available_set.rb:  Undent for style

    * lib/rubygems/dependency_installer.rb:  Pick latest prerelease gem to
      install.  Fixes RubyGems bug #468.

    * test/rubygems/test_gem_dependency_installer.rb:  Test for the above.

    * lib/rubygems/dependency_installer.rb:  Don't display "Done installing
      documentation" if documentation will not be installed.

    * lib/rubygems/rdoc.rb:  ditto

    * lib/rubygems/dependency_list.rb:  Use Array#concat for Ruby 1.x
      performance.

    * lib/rubygems/installer.rb:  Use formatted program name when comparing
      executables.  RubyGems pull request #471

    * test/rubygems/test_gem_installer.rb:  Test for the above.

    * lib/rubygems/package.rb:  Use more explicit feature check to work
      around JRuby bug #552

    * lib/rubygems/ssl_certs/GeoTrust_Global_CA.pem:  Added GeoTrust root
      certificate.

    * test/rubygems/test_gem_source_list.rb:  Use "example" instead of real
      hostname

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39793 b2dd03c8-39d4-4d8f-98ff-823fe69b080e