Use "package:" imports for pub.

test/barback/fails_if_no_default_dirs_test.dart

Index: test/barback/fails_if_no_default_dirs_test.dart
diff --git a/test/barback/fails_if_no_default_dirs_test.dart b/test/barback/fails_if_no_default_dirs_test.dart
index 3b0aa972f1aa9f6505e92a1a81da90e5753b9a32..5e2338c2c6769a00d969e453aa0541f92cb850a5 100644
--- a/test/barback/fails_if_no_default_dirs_test.dart
+++ b/test/barback/fails_if_no_default_dirs_test.dart
@@ -2,9 +2,9 @@
 // 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:pub/src/exit_codes.dart' as exit_codes;
 import 'package:scheduled_test/scheduled_test.dart';
 
-import '../../lib/src/exit_codes.dart' as exit_codes;
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';