# File lib/rdoc/rdoc.rb, line 230
  def update_output_dir(op_dir, time, last = {})
    return if @options.dry_run or not @options.update_output_dir

    open output_flag_file(op_dir), "w" do |f|
      f.puts time.rfc2822
      last.each do |n, t|
        f.puts "#{n}\t#{t.rfc2822}"
      end
    end
  end