make_destination_dirs

# File lib/rubygems/commands/setup_command.rb, line 328
  def make_destination_dirs(install_destdir)
    lib_dir, bin_dir = Gem.default_rubygems_dirs

    unless lib_dir
      lib_dir, bin_dir = generate_default_dirs(install_destdir)
    end

    mkdir_p lib_dir
    mkdir_p bin_dir

    return lib_dir, bin_dir
  end