I see this in logs on server shutdown:

```
2022.01.30 02:51:22.856463 [ 755777 ] {} <Error> void DB::MergeTreeBackgroundExecutor<DB::MergeMutateRuntimeQueue>::routine(DB::TaskRuntimeDataPtr) [Queue = DB::MergeMutateRuntimeQueue]: Code: 236. DB::Exception: Cancelled merging parts.
```

but it's not an error.

Log level should be changed and it should not show stack trace.
return;
    }
    {
        std::lock_guard guard(mutex);
        erase_from_active();
        has_tasks.notify_one();
        try
        {
            ALLOW_ALLOCATIONS_IN_SCOPE;
            
            
            
            item->task->onCompleted();
        }
        catch (...)
        {
            tryLogCurrentException(__PRETTY_FUNCTION__);
        }
        
        
        
        
        
        item->task.reset();
        item->is_done.set();
        item = nullptr;
    }
}
template <class Queue>
void MergeTreeBackgroundExecutor<Queue>::threadFunction()