relax error message format
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52269 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
relax error message format
message format. [Feature #9025], [ruby-core:71178] [Bug #11617]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52269 b2dd03c8-39d4-4d8f-98ff-823fe69b080e