message: Use relative paths in Checkpoint protos from tf.train.Checkpoint.save()
  This makes it consistent with tf.train.CheckpointManager.
diff: @@ -1360,7 +1360,8 @@ class Checkpoint(tracking.AutoTrackable):
  checkpoint_management.update_checkpoint_state_internal(
  save_dir=os.path.dirname(file_prefix),
  model_checkpoint_path=file_path,
  - all_model_checkpoint_paths=[file_path])
  + all_model_checkpoint_paths=[file_path],
  + save_relative_paths=True)
  return file_path
  def restore(self, save_path):
  