Fix bug in prebuilt.py where None is substituted into a string.

buildbot/prebuilt.py

 #!/usr/bin/python
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import datetime
 import multiprocessing
 import optparse
 import os
 import re
@@ skipping 478 matching lines @@
 
     remote_location = '%s/%s' % (self._upload_location.rstrip('/'), url_suffix)
     if remote_location.startswith('gs://'):
       # Build list of files to upload.
       upload_files = GenerateUploadDict(package_path, remote_location, uploads)
       remote_file = '%s/Packages' % remote_location.rstrip('/')
       upload_files[tmp_packages_file.name] = remote_file
 
       failed_uploads = RemoteUpload(self._acl, upload_files)
       if len(failed_uploads) > 1 or (None not in failed_uploads):
-        error_msg = ['%s -> %s\n' % args for args in failed_uploads]
+        error_msg = ['%s -> %s\n' % args for args in failed_uploads if args]
         raise UploadFailed('Error uploading:\n%s' % error_msg)
     else:
       pkgs = ' '.join(p['CPV'] + '.tbz2' for p in uploads)
       ssh_server, remote_path = remote_location.split(':', 1)
       d = { 'pkg_index': tmp_packages_file.name,
             'pkgs': pkgs,
             'remote_packages': '%s/Packages' % remote_location.rstrip('/'),
             'remote_path': remote_path.rstrip('/'),
             'remote_location': remote_location.rstrip('/'),
             'ssh_server': ssh_server }
@@ skipping 171 matching lines @@
     uploader._SyncHostPrebuilts(options.build_path, version, options.key,
                                 options.git_sync, options.sync_binhost_conf)
 
   if options.board:
     uploader._SyncBoardPrebuilts(options.board, options.build_path, version,
                                  options.key, options.git_sync,
                                  options.sync_binhost_conf)
 
 if __name__ == '__main__':
   main()