Don't implicitly run "pub get".

lib/src/barback/asset_environment.dart

 // Copyright (c) 2014, 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.barback.asset_environment;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:barback/barback.dart';
@@ skipping 56 matching lines @@
   static Future<AssetEnvironment> create(Entrypoint entrypoint,
       BarbackMode mode, {WatcherType watcherType, String hostname, int basePort,
       Iterable<String> packages, Iterable<AssetId> entrypoints,
       Map<String, String> environmentConstants, bool useDart2JS: true}) {
     if (watcherType == null) watcherType = WatcherType.NONE;
     if (hostname == null) hostname = "localhost";
     if (basePort == null) basePort = 0;
     if (environmentConstants == null) environmentConstants = {};
 
     return log.progress("Loading asset environment", () async {
-      var graph = await entrypoint.loadPackageGraph();
-      graph = _adjustPackageGraph(graph, mode, packages);
+      var graph = _adjustPackageGraph(entrypoint.packageGraph, mode, packages);
       var barback = new Barback(new PubPackageProvider(graph));
       barback.log.listen(_log);
 
       var environment = new AssetEnvironment._(graph, barback, mode,
           watcherType, hostname, basePort, environmentConstants);
 
       await environment._load(entrypoints: entrypoints, useDart2JS: useDart2JS);
       return environment;
     }, fine: true);
   }
@@ skipping 701 matching lines @@
   String toString() => "polling";
 }
 
 class _NoneWatcherType implements WatcherType {
   const _NoneWatcherType();
 
   DirectoryWatcher create(String directory) => null;
 
   String toString() => "none";
 }