# File lib/git/lib.rb, line 96
    def revparse(string)
      return string if string =~ /[A-Fa-f0-9]{40}/  # passing in a sha - just no-op it
      rev = ['head', 'remotes', 'tags'].map do |d|
        File.join(@git_dir, 'refs', d, string)
      end.find do |path|
        File.file?(path)
      end
      return File.read(rev).chomp if rev
      command('rev-parse', string)
    end