The following bug has been opened in debian
It seems that once a .uuid file has been created, it's never removed.
Shouldn't fc-cache remove the files from empty directories, I guess that would already help
(In reply to Laurent Bigonville from comment #0)
> Shouldn't fc-cache remove the files from empty directories, I guess that
> would already help
It's hard to figure out if the target directory is going to be removed or became empty tentatively. fontconfig is watching places to detect updates. it will removes invalid caches though that happens only when the coresponding directory has been removed.
I'll take a look to understand further more.
Okay, fixed in git f5dd851