message: Remove warnings for copy_op_to_graph.
diff: @@ -201,7 +201,7 @@ def copy_op_to_graph(org_instance, to_graph, variables, scope=''):
  #An instance of tensorflow.core.framework.node_def_pb2.NodeDef, it
  #stores String-based info such as name, device and type of the op.
  #Unique to every Operation instance.
  - new_node_def = deepcopy(op._node_def)
  + new_node_def = deepcopy(op.node_def)
  #Change the name
  new_node_def.name = new_name
  @@ -211,7 +211,7 @@ def copy_op_to_graph(org_instance, to_graph, variables, scope=''):
  #Make a copy of the op_def too.
  #Its unique to every _type_ of Operation.
  - op_def = deepcopy(op._op_def)
  + op_def = deepcopy(op.op_def)
  #Initialize a new Operation instance
  new_op = ops.Operation(new_node_def, to_graph, new_inputs, output_types,
  