Problem with ksycoca not being regenerated under flatpak

[Albert Astals Cid]

flatpak mounts all files as if created on January 1st 1970.

This has the unfortunate effect that when we add new plugins to a flatpak (i.e. we just added markdown preview support in kate), they are not seen because ksycoca doesn't feel the need to regenerate itself (the sycoca file for flatpak is written "outside" flatpak container and thus has a newer date).

I remember talking about this probably a year ago at least with Aleix, but i guess we did not come up with any solution since it's still broken :D

I don't know much about sycoca, but can we make it so the cache always get regenerated on app launch when run under flatpak?

Cheers,
  Albert