message: Change return of the update op to be a no-op
diff: @@ -676,7 +676,8 @@ class Mean(Metric):
  update_total_op = state_ops.assign_add(self.total, values)
  with ops.control_dependencies([update_total_op]):
  update_count_op = state_ops.assign_add(self.count, num_values)
  - return ops.convert_to_tensor(update_count_op)
  + with ops.control_dependencies([update_count_op]):
  + return control_flow_ops.no_op()
  def result(self):
  return math_ops.div_no_nan(self.total, self.count)
  