install_lib (Gem::Commands::SetupCommand)

    # File lib/rubygems/commands/setup_command.rb, line 217
      def install_lib(lib_dir)
        say "Installing RubyGems" if @verbose

        Dir.chdir 'lib' do
          lib_files = Dir[File.join('**', '*rb')]

          lib_files.each do |lib_file|
            dest_file = File.join lib_dir, lib_file
            dest_dir = File.dirname dest_file
            mkdir_p dest_dir unless File.directory? dest_dir

            install lib_file, dest_file, :mode => 0644
          end
        end
      end