merges r22247 from trunk into ruby_1_9_1. update rdoc [ruby-core:20407] #835
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@22530 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merges r22247 from trunk into ruby_1_9_1.
update rdoc [ruby-core:20407] #835
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@22530 b2dd03c8-39d4-4d8f-98ff-823fe69b080e