keyword ($Id$). ProgName with revision number was written in the 
  header line of each logfile for ease of tracking what version user
  is using in troubleshooting.  Logger is already stable enough.

I commit this on confirmation from Shyouhei.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8_7@31806 b2dd03c8-39d4-4d8f-98ff-823fe69b080e