change "illegal" to "invalid" in a context which doesn' t against a law. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14736 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
change "illegal" to "invalid" in a context which doesn' t against a law. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14736 b2dd03c8-39d4-4d8f-98ff-823fe69b080e