Take Sam Elkhateeb's path for "path" dependencies and clean it up some.

utils/pub/system_cache.dart

Index: utils/pub/system_cache.dart
diff --git a/utils/pub/system_cache.dart b/utils/pub/system_cache.dart
index 13e6b8d68db8d6ca2119339b00abd2c61cb32fc1..fd431171cf43c81a655654df49832b273d26b315 100644
--- a/utils/pub/system_cache.dart
+++ b/utils/pub/system_cache.dart
@@ -13,6 +13,7 @@ import 'io.dart';
 import 'io.dart' as io show createTempDir;
 import 'log.dart' as log;
 import 'package.dart';
+import 'path_source.dart';
 import 'pubspec.dart';
 import 'sdk_source.dart';
 import 'source.dart';
@@ -46,9 +47,10 @@ class SystemCache {
   /// Creates a system cache and registers the standard set of sources.
   factory SystemCache.withSources(String rootDir) {
     var cache = new SystemCache(rootDir);
-    cache.register(new SdkSource());
     cache.register(new GitSource());
     cache.register(new HostedSource());
+    cache.register(new PathSource());
+    cache.register(new SdkSource());
     cache.sources.setDefault('hosted');
     return cache;
   }