message: Update docstring for tf.train.init_from_checkpoint
  This fix updates docstring for tf.train.init_from_checkpoint,
  to match the actual implementation. (thanks sharvil)
  This fix fixes 24756.
diff: @@ -180,8 +180,8 @@ def init_from_checkpoint(ckpt_dir_or_file, assignment_map):
  (in default graph).
  Raises:
  - tf.errors.OpError: If missing checkpoints or tensors in checkpoints.
  - ValueError: If missing variables in current graph.
  + ValueError: If missing variables in current graph, or if missing
  + checkpoints or tensors in checkpoints.
  """
  if distribution_strategy_context.get_cross_replica_context():
  _init_from_checkpoint(None, ckpt_dir_or_file, assignment_map)
  