Fontconfig error: No writable cache directories

[Karl Berry]

      │ Fontconfig error: No writable cache directories

Seems like this error would be coming from the system? It's not like
tlmgr tries to call fontconfig while updating packages (or ever, as far
as I recall). Is it repeatable? I guess we'll find out tomorrow.

In any event, I can't think of any changes we've made that would change
this. Maybe you, or some process, cleaned up some "cache directories"
(whatever they are)? --best, karl.