that causes YAML serialization problem for Exception.
Exception#initialize doesn't use visible instance variable for
the exception message, so call the method with the message.
patched by Jingwen Owen Ou <jingweno AT gmail.com>.
http://github.com/ruby/ruby/pull/41
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@34908 b2dd03c8-39d4-4d8f-98ff-823fe69b080e