Revert "Revert "Use native async/await support in pub.""

sdk/lib/_internal/pub_generated/test/get/git/check_out_unfetched_revision_of_cached_repo_test.dart

-// Copyright (c) 2012, 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 'package:path/path.dart' as p;
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../../../lib/src/io.dart';
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  // Regression test for issue 20947.
-  integration(
-      'checks out an unfetched and locked revision of a cached ' 'repository',
-      () {
-    ensureGit();
-
-    // In order to get a lockfile that refers to a newer revision than is in the
-    // cache, we'll switch between two caches. First we ensure that the repo is
-    // in the first cache.
-    d.git('foo.git', [d.libDir('foo'), d.libPubspec('foo', '1.0.0')]).create();
-
-    d.appDir({
-      "foo": {
-        "git": "../foo.git"
-      }
-    }).create();
-
-    pubGet();
-
-    // Switch to a new cache.
-    schedule(
-        () =>
-            renameDir(p.join(sandboxDir, cachePath), p.join(sandboxDir, "$cachePath.old")));
-
-    // Make the lockfile point to a new revision of the git repository.
-    d.git(
-        'foo.git',
-        [d.libDir('foo', 'foo 2'), d.libPubspec('foo', '1.0.0')]).commit();
-
-    pubUpgrade(output: contains("Changed 1 dependency!"));
-
-    // Switch back to the old cache.
-    schedule(() {
-      var cacheDir = p.join(sandboxDir, cachePath);
-      deleteEntry(cacheDir);
-      renameDir(p.join(sandboxDir, "$cachePath.old"), cacheDir);
-    });
-
-    // Get the updated version of the git dependency based on the lockfile.
-    pubGet();
-
-    d.dir(
-        cachePath,
-        [
-            d.dir(
-                'git',
-                [
-                    d.dir('cache', [d.gitPackageRepoCacheDir('foo')]),
-                    d.gitPackageRevisionCacheDir('foo'),
-                    d.gitPackageRevisionCacheDir('foo', 2)])]).validate();
-
-    d.dir(
-        packagesPath,
-        [d.dir('foo', [d.file('foo.dart', 'main() => "foo 2";')])]).validate();
-  });
-}