message: Clear the invocation results in the buffer before retoring
diff: @@ -148,6 +148,7 @@ class ParallelMapIterator : public DatasetBaseIterator {
  int64 invocation_results_size;
  TF_RETURN_IF_ERROR(reader->ReadScalar(full_name("invocation_results.size"),
  &invocation_results_size));
  + if (!invocation_results_.empty()) invocation_results_.clear();
  for (size_t i = 0; i < invocation_results_size; i++) {
  invocation_results_.push_back(std::make_shared<InvocationResult>());
  auto& result = *invocation_results_.back();
  