Start pulling pub from its own repo.

sdk/lib/_internal/pub/test/global/binstubs/explicit_executables_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.
-
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  integration("only creates binstubs for the listed executables", () {
-    d.dir("foo", [
-      d.pubspec({
-        "name": "foo",
-        "executables": {
-          "one": "script",
-          "two": "script",
-          "three": "script"
-        }
-      }),
-      d.dir("bin", [
-        d.file("script.dart", "main() => print('ok');")
-      ])
-    ]).create();
-
-    schedulePub(args: [
-      "global", "activate", "--source", "path", "../foo",
-      "-x", "one", "--executable", "three"
-    ], output: contains("Installed executables one and three."));
-
-    d.dir(cachePath, [
-      d.dir("bin", [
-        d.matcherFile(binStubName("one"),
-            contains("pub global run foo:script")),
-        d.nothing(binStubName("two")),
-        d.matcherFile(binStubName("three"),
-            contains("pub global run foo:script"))
-      ])
-    ]).validate();
-  });
-}