anchor.diff:      final base64data = base64Encode(utf8.encode(message.toString()));
       final attributes = {
         if (chunk == chunks.last) 'num_chunks': chunks.length.toString(),
  -      if (buildbucketID != null) 'buildbucket_id': buildbucketID
  +      if (buildbucketID != null) 'buildbucket_id': buildbucketID,
  +      if (baseRevision != null) 'base_revision': baseRevision,
       };
       final jsonMessage = jsonEncode({
         'messages': [
  
positive.code:   final lines = await File(options['result_file']).readAsLines();
    final token = await File(options['auth_token']).readAsString();
    final buildbucketID = options['id'];
    if (lines.isEmpty) {
      print('No results in input file');
      return;
  
negative.code:   parser.addOption('result_file',
        abbr: 'f', help: 'File containing the results to send');
    parser.addOption('id', abbr: 'i', help: 'Buildbucket ID of this build');
    parser.addOption('base_revision', help: 'A try build\'s patch base');
  
    final options = parser.parse(args);
    if (options['help']) {
  