fix a typo

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42578 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
fix typos

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42579 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
fix a typo

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42580 b2dd03c8-39d4-4d8f-98ff-823fe69b080e