install (Gem::DependencyInstaller)

    # File lib/rubygems/dependency_installer.rb, line 215
      def install
        spec_dir = File.join @install_dir, 'specifications'
        source_index = Gem::SourceIndex.from_gems_in spec_dir

        @gems_to_install.each do |spec|
          last = spec == @gems_to_install.last
          # HACK is this test for full_name acceptable?
          next if source_index.any? { |n,_| n == spec.full_name } and not last

          say "Installing gem #{spec.full_name}" if Gem.configuration.really_verbose

          _, source_uri = @specs_and_sources.assoc spec
          local_gem_path = download spec, source_uri

          inst = Gem::Installer.new local_gem_path,
                                    :env_shebang => @env_shebang,
                                    :force => @force,
                                    :format_executable => @format_executable,
                                    :ignore_dependencies => @ignore_dependencies,
                                    :install_dir => @install_dir,
                                    :security_policy => @security_policy,
                                    :wrappers => @wrappers,
                                    :skip_dependencies => @skip_dependencies

          spec = inst.install

          @installed_gems << spec
        end
      end