message: Make newly added parameter for FoldFusedBatchNormGrad optional
diff: @@ -490,7 +490,7 @@ def _CloneWithNewOperands(layer_op, input_tensor, weight_tensor,
  @ops.RegisterGradient('FoldFusedBatchNormGrad')
  def _FoldFusedBatchNormGrad(op, unused_grad_y, grad_mean, grad_var, unused_1,
  - unused_2, unused_3):
  + unused_2, unused_3=None):
  x = op.inputs[0]
  n = math_ops.cast(
  array_ops.size(x) / array_ops.size(grad_mean), dtypes.float32)
  