message: Unprotect SignatureDef default input names.
diff: @@ -51,9 +51,11 @@ SIGNATURE_KEY_MAP = mode_keys.ModeKeyMap(**{
  ModeKeys.TRAIN: signature_constants.DEFAULT_TRAIN_SIGNATURE_DEF_KEY,
  ModeKeys.TEST: signature_constants.DEFAULT_EVAL_SIGNATURE_DEF_KEY})
  -_SINGLE_FEATURE_DEFAULT_NAME = 'feature'
  -_SINGLE_RECEIVER_DEFAULT_NAME = 'input'
  -_SINGLE_LABEL_DEFAULT_NAME = 'label'
  +# Default names used in the SignatureDef input map, which maps strings to
  +# TensorInfo protos.
  +SINGLE_FEATURE_DEFAULT_NAME = 'feature'
  +SINGLE_RECEIVER_DEFAULT_NAME = 'input'
  +SINGLE_LABEL_DEFAULT_NAME = 'label'
  ### Below utilities are specific to SavedModel exports.
  @@ -89,7 +91,7 @@ def build_all_signature_defs(receiver_tensors,
  ValueError: if export_outputs is not a dict
  """
  if not isinstance(receiver_tensors, dict):
  - receiver_tensors = {_SINGLE_RECEIVER_DEFAULT_NAME: receiver_tensors}
  + receiver_tensors = {SINGLE_RECEIVER_DEFAULT_NAME: receiver_tensors}
  if export_outputs is None or not isinstance(export_outputs, dict):
  raise ValueError('export_outputs must be a dict and not'
  '{}'.format(type(export_outputs)))
  @@ -109,7 +111,7 @@ def build_all_signature_defs(receiver_tensors,
  six.iteritems(receiver_tensors_alternatives)):
  if not isinstance(receiver_tensors_alt, dict):
  receiver_tensors_alt = {
  - _SINGLE_RECEIVER_DEFAULT_NAME: receiver_tensors_alt
  + SINGLE_RECEIVER_DEFAULT_NAME: receiver_tensors_alt
  }
  for output_key, export_output in export_outputs.items():
  signature_name = '{}:{}'.format(receiver_name or 'None', output_key or
  