message: handle move of copy_handle_data
  Summary:
  Ref T57439
  TF2.6 Only
  Reviewers: #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, jackh
  Maniphest Tasks: T57439
diff: @@ -26,8 +26,8 @@ from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import cond_v2
  from tensorflow.python.ops import control_flow_util
  from tensorflow.python.ops import control_flow_util_v2 as util
  -from tensorflow.python.ops import custom_gradient
  from tensorflow.python.ops import gradients_util
  +from tensorflow.python.ops import handle_data_util
  """
  These gradient function should *never* be called directly.
  """
  @@ -187,7 +187,7 @@ def _get_gradients_for_function(op, *grads):
  func_graph = _get_func_graph(fwd_op)
  assert func_graph.outer_graph == op.graph
  for external_t, internal_t in zip(inputs, func_graph.inputs):
  - custom_gradient.copy_handle_data(external_t, internal_t)
  + handle_data_util.copy_handle_data(external_t, internal_t)
  func_graph.reset_captures(zip(inputs, func_graph.inputs))
  