Start pulling pub from its own repo.

sdk/lib/_internal/pub/test/barback/fails_if_dir_arg_does_not_exist_test.dart

-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS d.file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../../lib/src/exit_codes.dart' as exit_codes;
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-import 'utils.dart';
-
-main() {
-  initConfig();
-
-  setUp(() {
-    d.dir(appPath, [
-      d.appPubspec(),
-      d.dir("bar", [
-        d.file("file.txt", "contents")
-      ])
-    ]).create();
-  });
-
-  pubBuildAndServeShouldFail("if a specified directory doesn't exist",
-      args: ["foo", "bar", "baz"],
-      error: 'Directories "foo" and "baz" do not exist.',
-      exitCode: exit_codes.DATA);
-}