message: remove useless temporary variable in prefetch dataset
diff: @@ -282,8 +282,6 @@ class PrefetchDatasetOp::Dataset : public DatasetBase {
  RecordStart(ctx.get());
  auto cleanup = gtl::MakeCleanup([this, ctx] { RecordStop(ctx.get()); });
  while (true) {
  - std::vector<Tensor> value;
  -
  // 1. Wait for a slot in the buffer.
  {
  mutex_lock l(mu_);
  