# File lib/rubygems/gem_commands.rb, line 997
    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