logger.rb: simplify
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47272 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
logger.rb: simplify
format so that it can be shared.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47272 b2dd03c8-39d4-4d8f-98ff-823fe69b080e