Onion Location on Android is ignored

A while ago I plumbed privacy.prioritizeonions.enabled on Android, because it was an easy win to add a "Prioritize .onion sites" in the settings.

For a while it worked, and even now if you enable it you'll get redirected to the onion site.

However, for some reason, the correct value isn't read when you launch your browser again.

At least, security level and spoof English are still working.