message: Make exported MetaGraphDefs deterministic
  Nondeterministic serialized protos hurt caching.
diff: @@ -71,5 +71,6 @@ def write_graph(graph_or_graph_def, logdir, name, as_text=True):
  text_format.MessageToString(
  graph_def, float_format=''))
  else:
  - file_io.atomic_write_string_to_file(path, graph_def.SerializeToString())
  + file_io.atomic_write_string_to_file(
  + path, graph_def.SerializeToString(deterministic=True))
  return path
  