Start pulling pub from its own repo.

sdk/lib/_internal/pub/test/cache/add/no_matching_version_test.dart

-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS 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.
-
-library pub_tests;
-
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  integration('fails if no version matches the version constraint', () {
-    servePackages((builder) {
-      builder.serve("foo", "1.2.2");
-      builder.serve("foo", "1.2.3");
-    });
-
-    schedulePub(args: ["cache", "add", "foo", "-v", ">2.0.0"],
-        error: 'Package foo has no versions that match >2.0.0.',
-        exitCode: 1);
-  });
-}