This created weird cases in logs which are very hard to understand. The
one which really got me was this:
```
[runtime] 2023-08-13 07:48:27 [verbose]: Invalidating working beatmap cache for unknown artist - unknown title (Dummy)
```
Which looks like a dummy working beatmap was invalidated, but it turns
out that's just the local user which was populated when creating a new
local beatmap.
