message: Add back python gradient
diff: @@ -2135,6 +2135,12 @@ class _UnreadVariable(BaseResourceVariable):
  return self._parent_op
  +@ops.RegisterGradient("ReadVariableOp")
  +def _ReadGrad(_, grad):
  + """Gradient for read op."""
  + return grad
  +
  +
  def variable_shape(handle, out_type=dtypes.int32):
  if getattr(handle, "_handle_data",
  None) is None or not handle._handle_data.is_set: # pylint: disable=protected-access
  