Store the async-await compiled pub code directly in the repo.

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

+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();
+  integration("doesn't re-fetch a repository if nothing changes", () {
+    ensureGit();
+    var repo =
+        d.git('foo.git', [d.libDir('foo'), d.libPubspec('foo', '1.0.0')]);
+    repo.create();
+    d.appDir({
+      "foo": {
+        "git": {
+          "url": "../foo.git"
+        }
+      }
+    }).create();
+    pubGet();
+    d.dir(
+        packagesPath,
+        [d.dir('foo', [d.file('foo.dart', 'main() => "foo";')])]).validate();
+    schedule(() => deleteEntry(p.join(sandboxDir, 'foo.git')));
+    pubGet();
+    d.dir(
+        packagesPath,
+        [d.dir('foo', [d.file('foo.dart', 'main() => "foo";')])]).validate();
+  });
+}