git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@11265 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
holds duplicate values. [issue: #6444]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@11265 b2dd03c8-39d4-4d8f-98ff-823fe69b080e