Include stderr on git failure.

utils/pub/pub.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.
 
 /**
  * The main entrypoint for the pub command line application.
  */
 #library('pub');
 
 #import('../../pkg/args/lib/args.dart');
@@ skipping 122 matching lines @@
   }
 
   print('');
   print('Use "pub help [command]" for more information about a command.');
 }
 
 void printVersion() {
   print('Pub $pubVersion');
 }
 
-class PubCommand {
+abstract class PubCommand {
   SystemCache cache;
   ArgResults globalOptions;
   ArgResults commandOptions;
 
   Entrypoint entrypoint;
 
   /**
    * A one-line description of this command.
    */
   abstract String get description;
@@ skipping 110 matching lines @@
     if (exception is HttpException || exception is HttpParserException ||
         exception is SocketIOException || exception is PubHttpException) {
       return exit_codes.UNAVAILABLE;
     } else if (exception is FormatException) {
       return exit_codes.DATA;
     } else {
       return 1;
     }
   }
 }