Initialize ID
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55540 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Initialize ID
ID for theha class variable once at first.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55540 b2dd03c8-39d4-4d8f-98ff-823fe69b080e