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merge revision(s) 39597: [Backport #7991]

    * lib/rubygems.rb:  Bump version to 2.0.1 for upcoming bugfix release

    * lib/rubygems/ext/ext_conf_builder.rb:  Restore ruby 1.8 compatibility
      for [Bug #9698]

    * test/rubygems/test_gem_installer.rb:  Ditto.

    * lib/rubygems/package.rb:  Restore ruby 1.8 compatibility.

    * test/rubygems/test_gem_dependency_installer.rb:  Fix warnings

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39795 b2dd03c8-39d4-4d8f-98ff-823fe69b080e