message: Overriding existing values failed silently
diff: @@ -70,8 +70,8 @@ bool LocalMemoryBackend<TKey>::insert(const std::string& table_name, const size_
  const TKey* const keys_end = &keys[num_pairs];
  for (; keys != keys_end; keys++) {
  const char* const values_next = &values[value_size];
  - table.emplace(std::piecewise_construct, std::forward_as_tuple(*keys),
  - std::forward_as_tuple(values, values_next));
  + const auto& it = table.try_emplace(*keys).first;
  + it->second.assign(values, values_next);
  values = values_next;
  }
  const size_t num_inserts = num_pairs;
  @@ -276,8 +276,8 @@ bool ParallelLocalMemoryBackend<TKey>::insert(const std::string& table_name, con
  for (const TKey* k = keys; k != keys_end; k++) {
  if (*k % num_partitions_ == partition) {
  const char* const v = &values[(k - keys) * value_size];
  - table.emplace(std::piecewise_construct, std::forward_as_tuple(*k),
  - std::forward_as_tuple(v, &v[value_size]));
  + const auto& it = table.try_emplace(*k).first;
  + it->second.assign(v, &v[value_size]);
  num_inserts++;
  }
  }
  