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

test/implicit_barback_dependency_test.dart

 // Copyright (c) 2013, 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 'package:pub/src/barback.dart' as barback;
 import 'package:pub_semver/pub_semver.dart';
 
 import 'descriptor.dart' as d;
 import 'test_pub.dart';
 
@@ skipping 20 matching lines @@
         builder.serve("stack_trace", stackTraceVersion);
         builder.serve("async", asyncVersion);
       });
 
       d.appDir({
         "barback": "any"
       }).create();
 
       pubCommand(command);
 
-      d.packagesDir({
-        "barback": nextPatch
+      d.appPackagesFile({
+        "async": asyncVersion,
+        "barback": nextPatch,
+        "source_span": sourceSpanVersion,
+        "stack_trace": stackTraceVersion
       }).validate();
     });
 
     integration("discovers transitive dependency on barback", () {
       servePackages((builder) {
         builder.serve("barback", previous);
         builder.serve("barback", current);
         builder.serve("barback", nextPatch);
         builder.serve("barback", max);
         builder.serve("source_span", sourceSpanVersion);
         builder.serve("stack_trace", stackTraceVersion);
         builder.serve("async", asyncVersion);
       });
 
       d.dir("foo", [
         d.libDir("foo", "foo 0.0.1"),
         d.libPubspec("foo", "0.0.1", deps: {
           "barback": "any"
         })
       ]).create();
 
       d.appDir({
         "foo": {"path": "../foo"}
       }).create();
 
       pubCommand(command);
 
-      d.packagesDir({
+      d.appPackagesFile({
+        "async": asyncVersion,
         "barback": nextPatch,
-        "foo": "0.0.1"
+        "source_span": sourceSpanVersion,
+        "stack_trace": stackTraceVersion,
+        "foo": "../foo"
       }).validate();
     });
 
     integration("pub's implicit constraint uses the same source and "
         "description as a dependency override", () {
       servePackages((builder) {
         builder.serve("source_span", sourceSpanVersion);
         builder.serve("stack_trace", stackTraceVersion);
         builder.serve("async", asyncVersion);
       });
 
       d.dir('barback', [
         d.libDir('barback', 'barback $current'),
         d.libPubspec('barback', current),
       ]).create();
 
       d.dir(appPath, [
         d.pubspec({
           "name": "myapp",
           "dependency_overrides": {
             "barback": {"path": "../barback"}
           }
         })
       ]).create();
 
       pubCommand(command);
 
-      d.packagesDir({
-        "barback": current
+      d.appPackagesFile({
+        "async": asyncVersion,
+        "barback": "../barback",
+        "source_span": sourceSpanVersion,
+        "stack_trace": stackTraceVersion,
       }).validate();
     });
   });
 
   integration("unlock if the locked version doesn't meet pub's constraint", () {
     servePackages((builder) {
       builder.serve("barback", previous);
       builder.serve("barback", current);
       builder.serve("source_span", sourceSpanVersion);
       builder.serve("stack_trace", stackTraceVersion);
       builder.serve("async", asyncVersion);
     });
 
     d.appDir({"barback": "any"}).create();
 
     // Hand-create a lockfile to pin barback to an older version.
     createLockFile("myapp", hosted: {
       "barback": previous
     });
 
     pubGet();
 
     // It should be upgraded.
-    d.packagesDir({
-      "barback": current
+    d.appPackagesFile({
+      "async": asyncVersion,
+      "barback": current,
+      "source_span": sourceSpanVersion,
+      "stack_trace": stackTraceVersion,
     }).validate();
   });
 
   integration("includes pub in the error if a solve failed because there "
       "is no version available", () {
     servePackages((builder) {
       builder.serve("barback", previous);
       builder.serve("source_span", sourceSpanVersion);
       builder.serve("stack_trace", stackTraceVersion);
       builder.serve("async", asyncVersion);
@@ skipping 18 matching lines @@
     });
 
     d.appDir({"barback": previous}).create();
 
     pubGet(error: """
 Incompatible version constraints on barback:
 - myapp depends on version $previous
 - pub itself depends on version >=$current <$max""");
   });
 }