Ignore builders without result

Tools/Scripts/webkitpy/tool/commands/rebaseline.py

 # Copyright (c) 2010 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 305 matching lines @@
     # not overriding execute() - pylint: disable=W0223
 
     def __init__(self, options=None):
         super(AbstractParallelRebaselineCommand, self).__init__(options=options)
         self._builder_data = {}
 
     def builder_data(self):
         if not self._builder_data:
             for builder_name in self._release_builders():
                 builder = self._tool.buildbot.builder_with_name(builder_name)
-                self._builder_data[builder_name] = builder.latest_layout_test_results()
+                builder_results = builder.latest_layout_test_results()
+                if builder_results:
+                    self._builder_data[builder_name] = builder_results
+                else:
+                    _log.warning("No result for builder '%s'" % builder_name)
         return self._builder_data
 
     # The release builders cycle much faster than the debug ones and cover all the platforms.
     def _release_builders(self):
         release_builders = []
         for builder_name in builders.all_builder_names():
             if builder_name.find('ASAN') != -1:
                 continue
             port = self._tool.port_factory.get_from_builder_name(builder_name)
             if port.test_configuration().build_type == 'release':
@@ skipping 608 matching lines @@
             self._tool.scm().checkout_branch(old_branch_name)
         else:
             self._log_queue.put(self.QUIT_LOG)
         log_thread.join()
 
     def execute(self, options, args, tool):
         self._verbose = options.verbose
         while True:
             self._do_one_rebaseline()
             time.sleep(self.SLEEP_TIME_IN_SECONDS)