[Feature #6693]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36337 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
[Feature #6693]
variables starting with _. [ruby-core:46160][Feature #6693]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36337 b2dd03c8-39d4-4d8f-98ff-823fe69b080e