# File lib/git/lib.rb, line 95
    def revparse(string)
      if /\w{40}/.match(string)  # passing in a sha - just no-op it
        return string
      end
            
      head = File.join(@git_dir, 'refs', 'heads', string)
      return File.read(head).chomp if File.file?(head)

      head = File.join(@git_dir, 'refs', 'remotes', string)
      return File.read(head).chomp if File.file?(head)
      
      head = File.join(@git_dir, 'refs', 'tags', string)
      return File.read(head).chomp if File.file?(head)
      
      command('rev-parse', string)
    end