message: probably need to merge string heaps
diff: @@ -696,8 +696,9 @@ void SuperLargeHashTable::Merge(SuperLargeHashTable &other) {
  merge_entries -= this_entries;
  }
  assert(merge_entries == 0);
  -
  FlushMerge(addresses, hashes, group_idx);
  + string_heap.MergeHeap(other.string_heap);
  +
  Verify();
  }
  