message: Fix incorrect use of UpdateEdge for control edges during import
diff: @@ -462,10 +462,15 @@ StatusOr<Node*> ImporterBase::ReplaceWithPlaceholderNode(
  while (!input_node->out_edges().empty()) {
  const Edge* oe = *input_node->out_edges().begin();
  - TF_RETURN_IF_ERROR(graph_->UpdateEdge(
  - placeholder_node,
  - oe->src_output() == Graph::kControlSlot ? Graph::kControlSlot : 0,
  - oe->dst(), oe->dst_input()));
  + // UpdateEdge cannot be used with control edges.
  + if (oe->src_output() == Graph::kControlSlot) {
  + graph_->AddControlEdge(placeholder_node, oe->dst());
  + graph_->RemoveControlEdge(oe);
  + continue;
  + }
  +
  + TF_RETURN_IF_ERROR(
  + graph_->UpdateEdge(placeholder_node, 0, oe->dst(), oe->dst_input()));
  }
  graph_->RemoveNode(input_node);
  