message: Ensure to use tensor references when dealing with sets in TF 2.
diff: @@ -4516,9 +4516,13 @@ class Graph(object):
  return self._control_inputs_val
  def add_op(self, op):
  + if isinstance(op, Tensor):
  + op = op.experimental_ref()
  self._seen_nodes.add(op)
  def op_in_group(self, op):
  + if isinstance(op, Tensor):
  + op = op.experimental_ref()
  return op in self._seen_nodes
  def _push_control_dependencies_controller(self, controller):
  