message: Fix a race condition in EagerExecutor
diff: @@ -176,10 +176,10 @@ void EagerExecutor::NodeDone(core::RefCountPtr<NodeItem> item,
  const Status& status) {
  VLOG(3) << "Node Done: [id " << item->id << "] " << item->node->DebugString()
  << " with status: " << status.ToString();
  - DCHECK(item->state != NodeState::kDONE);
  std::vector<core::RefCountPtr<NodeItem>> items_to_destroy;
  {
  mutex_lock l(node_queue_mutex_);
  + DCHECK(item->state != NodeState::kDONE);
  auto previous_state = item->state;
  item->state = NodeState::kDONE;
  if (!status_.ok()) return;
  