# File lib/grit/commit.rb, line 264
    def patch_id
      show = @repo.git.show({}, @id)
      patch_line = @repo.git.native(:patch_id, :input => show)
      if patch_line =~ /^([0-9a-f]{40}) [0-9a-f]{40}\n$/
        $1
      else
        nil
      end
    end