APTX

I recently tried to scan BS again (I still don't have access to CS) on a new system and got the `FE_SET_TONE` error again. I reread this issue and found...

I get various forms of DeadlockException almost every time I sync files (last time I wrote a comment about it: https://github.com/nextcloud/server/issues/10473#issuecomment-650783226). I guess it's finally happening with MySQL as well....