Start pulling pub from its own repo.

sdk/lib/_internal/pub/test/run/runs_from_a_dependency_override_after_dependency_test.dart

-// Copyright (c) 2015, 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.
-
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-import '../serve/utils.dart';
-
-main() {
-  initConfig();
-  // Regression test for issue 23113
-  integration('runs a named Dart application in a dependency', () {
-    servePackages((builder) {
-      builder.serve('foo', '1.0.0', pubspec: {
-        'name': 'foo',
-        'version': '1.0.0'
-      }, contents: [
-        d.dir("bin", [
-          d.file("bar.dart", "main() => print('foobar');")
-        ])
-      ]);
-    });
-
-    d.dir(appPath, [
-      d.appPubspec({"foo": null})
-    ]).create();
-
-    pubGet();
-
-    var pub = pubRun(args: ["foo:bar"]);
-    pub.stdout.expect("foobar");
-    pub.shouldExit();
-
-    d.dir("foo", [
-      d.libPubspec("foo", "2.0.0"),
-      d.dir("bin", [
-        d.file("bar.dart", "main() => print('different');")
-      ])
-    ]).create();
-
-    d.dir(appPath, [
-      d.pubspec({
-        "name": "myapp",
-        "dependencies": {"foo": {"path": "../foo"}}
-      })
-    ]).create();
-
-    pubGet();
-
-    pub = pubRun(args: ["foo:bar"]);
-    pub.stdout.expect("different");
-    pub.shouldExit();
-  });
-}