Make "--no-packages-dir" the default.

test/get/relative_symlink_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.
 
 import 'dart:io';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   // Pub uses NTFS junction points to create links in the packages directory.
   // These (unlike the symlinks that are supported in Vista and later) do not
   // support relative paths. So this test, by design, will not pass on Windows.
   // So just skip it.
   if (Platform.operatingSystem == "windows") return;
 
   integration('uses a relative symlink for the self link', () {
     d.dir(appPath, [
       d.appPubspec(),
       d.libDir('foo')
     ]).create();
 
-    pubGet();
+    pubGet(args: ["--packages-dir"]);
 
     scheduleRename(appPath, "moved");
 
     d.dir("moved", [
       d.dir("packages", [
         d.dir("myapp", [
           d.file('foo.dart', 'main() => "foo";')
         ])
       ])
     ]).validate();
   });
 
   integration('uses a relative symlink for secondary packages directory', () {
     d.dir(appPath, [
       d.appPubspec(),
       d.libDir('foo'),
       d.dir("bin")
     ]).create();
 
-    pubGet();
+    pubGet(args: ["--packages-dir"]);
 
     scheduleRename(appPath, "moved");
 
     d.dir("moved", [
       d.dir("bin", [
         d.dir("packages", [
           d.dir("myapp", [
             d.file('foo.dart', 'main() => "foo";')
           ])
         ])
       ])
     ]).validate();
   });
 }