Comment 56 for bug 1690980

@Brian: It looks like blocking shutdown did work properly but the upgrade itself took longer than 15 minutes which is the current timeout. (see u-u.log)

I already filed a PR against u-u to bump the timeout to 30 mins: https://github.com/mvo5/unattended-upgrades/pull/69 , but in this case apt's timer kicks in (@Julian).