# File lib/rubygems/commands/update_command.rb, line 79
      def do_rubygems_update(version_string)
        update_dir = File.join(Gem.dir, "gems", "rubygems-update-#{version_string}")
        Dir.chdir(update_dir) do
          puts "Installing RubyGems #{version_string}"
          system "#{Gem.ruby} setup.rb"
        end
      end