Ceki - I haven't seen this now since writing last time, which is rather surprising. During that day (last Monday) I ran into it multiple times.

This is likely caused by some circumstances that have changed since. Until we can prove that this can be triggered in a reproducible way, there's not much to do about it. If someone (including me) can provide a reproducible repo that triggers the bug consequently, we could try looking further.

Until then, I think I'm fine with closing it. Thanks for the effort so far.