class Gem::Commands::UpdateCommand

def install_rubygems version # :nodoc:
  args = update_rubygems_arguments
  update_dir = File.join Gem.dir, 'gems', "rubygems-update-#{version}"
  Dir.chdir update_dir do
    say "Installing RubyGems #{version}"
    # Make sure old rubygems isn't loaded
    old = ENV["RUBYOPT"]
    ENV.delete("RUBYOPT") if old
    installed = system Gem.ruby, 'setup.rb', *args
    say "RubyGems system software updated" if installed
    ENV["RUBYOPT"] = old if old
  end
end