Comment # 4 on bug 937047 from Thorsten Kukuk

(In reply to Achim Gratz from comment #0)
> After a snapper boot rollback, the default btrfs subvolume has changed to
> the snapshot I've rolled back to.  This had several undesirable consequences:
>
> 1. Snapper stopped working since /.snapshots wasn't populated any more. 
> I've fixed that by adding the .snapshots subvolume to /etc/fstab.

This sounds like your system wasn't setup for rollback. Else /.snapshots should
have been added to /etc/fstab already. Could it be that this was an upgrade
from something older/short before rollback was fully introduced in openSUSE?

> 2. One of the snapshots listed by snapper is actually the new default
> subvolume, but that's not marked in any way.

When you called snapper rollback, snapper told you that this snapshot is the
new default root filesystem. What else do you expect?

> 3. Trying to delete that snapshot leaves the system in an unusable state
> with most filesystems unmounted.  You can only switch off hard at that
> point.  The snapper cleanup hasn't gotten to that snapshot yet, but when it
> does it might produce the same crash then.

snapper cleanup algorighm will not delete the subvolume with the current root
filesystem. So this is can really only happen if you try to manual delete that
snapshot.