Document workaround for partially applied automatic upgrade
As we see on #14754 sometimes an automated upgrade is partially applied and as a result the upgraded system behaves weirdly. That is occuring a lot recently according to help desk, but I’ve found no way to fix it yet (there’s a tentative fix ready in Git, that will be used first during the 3.9→3.10 upgrade but I’m not counting on it too much).
So IMO we should document a workaround: assuming I’ve upgraded to 3.6.2
and my Tails does not work anymore, I should add a line that contains
“3.6.2.squashfs” (without the quotes) at the end of
live/Tails.module (at the root of the Tails system partition). Adjust
the version number depending on what version one is upgrading to, e.g.
if users have the same problem after upgrading to 3.7, they should add a
line that contains “3.7.squashfs” instead. Presumably this must be done
from a non-Tails system (or from another, working Tails).
Feature Branch: doc/15557-upgrade-to-fix-upgrade