Add a Pub source for pub.dartlang.org.

utils/pub/pub.dart

Index: utils/pub/pub.dart
diff --git a/utils/pub/pub.dart b/utils/pub/pub.dart
index 37898c3adbbde4431419a077f334043b48012f5b..c0c346b48d4654d4d691b7a277d35af35a5040bf 100644
--- a/utils/pub/pub.dart
+++ b/utils/pub/pub.dart
@@ -16,6 +16,7 @@
 #import('git_source.dart');
 #import('package.dart');
 #import('pubspec.dart');
+#import('repo_source.dart');
 #import('sdk_source.dart');
 #import('source.dart');
 #import('source_registry.dart');
@@ -76,6 +77,8 @@ main() {
   var cache = new SystemCache(cacheDir);
   cache.sources.register(new SdkSource(sdkDir));
   cache.sources.register(new GitSource());
+  cache.sources.register(new RepoSource());
+  // TODO(nweiz): Make 'repo' the default once pub.dartlang.org exists
   cache.sources.setDefault('sdk');
 
   // Select the command.
@@ -168,6 +171,7 @@ class PubCommand {
         return commandFuture;
       } catch (var error) {
         handleError(error);
+        return new Future.immediate(null);
       }
     }).handleException(handleError);
   }