message: Update BatchNormGrad dummy literal to be all-zero instead of all-NaN
diff: @@ -1456,24 +1456,24 @@ Status NGraphEmitter::ProcessBatchNormGrad(HloInstruction* bng) {
  }
  // TODO(amprocte): We are temporarily supplying a fake value for beta here
  - // (all NaN, same shape/et as gamma), because XLA does not give beta to us.
  + // (all zero, same shape/et as gamma), because XLA does not give beta to us.
  // This should work because nGraph should not actually use beta. The nGraph
  // op may change to discard this parameter. Update this when nGraph does.
  - std::shared_ptr<ngraph::Node> ng_nan_scalar_op =
  + std::shared_ptr<ngraph::Node> ng_zero_scalar_op =
  std::make_shared<ngraph::op::Constant>(ng_gamma_op->get_element_type(),
  ngraph::Shape{},
  - std::vector<std::string>{"NAN"});
  + std::vector<std::string>{"0"});
  ngraph::AxisSet ng_broadcast_axes;
  for (size_t i = 0; i < ng_gamma_op->get_shape().size(); i++) {
  ng_broadcast_axes.insert(i);
  }
  - std::shared_ptr<ngraph::Node> ng_nan_tensor_op =
  + std::shared_ptr<ngraph::Node> ng_zero_tensor_op =
  std::make_shared<ngraph::op::Broadcast>(
  - ng_nan_scalar_op, ng_gamma_op->get_shape(), ng_broadcast_axes);
  + ng_zero_scalar_op, ng_gamma_op->get_shape(), ng_broadcast_axes);
  std::shared_ptr<ngraph::Node> ng_result_op =
  std::make_shared<ngraph::op::BatchNormBackprop>(
  - epsilon, ng_gamma_op, /*beta=*/ng_nan_tensor_op, ng_input_op,
  + epsilon, ng_gamma_op, /*beta=*/ng_zero_tensor_op, ng_input_op,
  ng_mean_op, ng_variance_op, ng_delta_op);
  std::shared_ptr<ngraph::Node> ng_input_delta_op =
  