message: Actually not a race - but this lock is unnecessary
diff: @@ -112,7 +112,6 @@ public:
  MergeSorter merge_sorter(global_sort_state, BufferManager::GetBufferManager(context));
  merge_sorter.PerformInMergeRound();
  // Finish task and act if all tasks are finished
  - lock_guard<mutex> state_guard(global_sort_state.lock);
  idx_t finished_tasks = ++parent.finished_tasks;
  if (finished_tasks == parent.total_tasks) {
  global_sort_state.CompleteMergeRound();
  