message: If the config fails to be saved, restore models as revived models.
  Fixes //third_party/py/telluride_decoding:infer_decoder_test
diff: @@ -290,7 +290,8 @@ class KerasObjectLoader(tf_load.Loader):
  model_is_functional_or_sequential = (
  metadata.get('is_graph_network', False) or
  metadata['class_name'] == 'Sequential')
  - if (generic_utils.LAYER_UNDEFINED_CONFIG_KEY in config or
  + if (config is None or
  + generic_utils.LAYER_UNDEFINED_CONFIG_KEY in config or
  not model_is_functional_or_sequential):
  return None # Revive as custom model.
  