persistence.conf lost, recoverable by reconfiguring
Once in a while this happens since many Tails, maybe the persistence.conf file gets broken.
But since Tails 1.8.2 many of such reports have been made, most of the times only rebooting normally (no emergency shutdown, nothing)
The Persistence is easily recovered by reconfiguring it again, with same passphrase.
I guess I should add a note on known issues, and that is how I will resolve this ticket. But I wanted the devs to know that (I think) something on 1.8.2 made the persistence.conf a little bit more fragile.
Not sure what will happen with Tails 2.0, maybe this dissapears.