message: Replace deprecated _control_inputs with remove/add to avoid warnings.
diff: @@ -471,9 +471,10 @@ def remove_control_inputs(op, cops):
  if cop not in op.control_inputs:
  raise ValueError("{} is not a control_input of {}".format(op.name,
  cop.name))
  + control_inputs = [cop for cop in op.control_inputs if cop not in cops]
  # pylint: disable=protected-access
  - op._control_inputs = [cop for cop in op._control_inputs if cop not in cops]
  - op._recompute_node_def()
  + op._remove_all_control_inputs()
  + op._add_control_inputs(control_inputs)
  # pylint: enable=protected-access
  @@ -496,9 +497,6 @@ def add_control_inputs(op, cops):
  if cop in op.control_inputs:
  raise ValueError("{} is already a control_input of {}".format(cop.name,
  op.name))
  - # pylint: disable=protected-access
  - op._control_inputs += cops
  - op._recompute_node_def()
  - # pylint: enable=protected-access
  + op._add_control_inputs(cops) # pylint: disable=protected-access
  remove_undocumented(__name__, _allowed_symbols)
  