Use relative symlinks for self links and secondary "packages" dirs.

utils/tests/pub/install/pub_install_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 'dart:io';
 
 import '../../../../pkg/unittest/lib/unittest.dart';
 import '../test_pub.dart';
 
 main() {
+  initConfig();
+
   group('requires', () {
     integration('a pubspec', () {
       dir(appPath, []).scheduleCreate();
 
       schedulePub(args: ['install'],
           error: new RegExp(r'^Could not find a file named "pubspec\.yaml"'),
           exitCode: 1);
     });
 
     integration('a pubspec with a "name" key', () {
@@ skipping 219 matching lines @@
           dir("packages", [
             dir("myapp", [
               file('foo.dart', 'main() => "foo";')
             ])
           ])
         ])
       ]).scheduleValidate();
     });
   });
 }