Comment 17 for bug 1803391

TTFN:
To add to (and correct) my earlier comments: after the updating shown there, the machine had to be rebooted manually. Checking /var/log/apt/term.log it appears that the upgrade did complete successfully:

Log started: 2021-01-07 13:28:19
(Reading database ... 151099 files and directories currently installed.)
Preparing to unpack .../libnss-systemd_237-3ubuntu10.43_i386.deb ...
Unpacking libnss-systemd:i386 (237-3ubuntu10.43) over (237-3ubuntu10.42) ...
Preparing to unpack .../libpam-systemd_237-3ubuntu10.43_i386.deb ...
Unpacking libpam-systemd:i386 (237-3ubuntu10.43) over (237-3ubuntu10.42) ...
Preparing to unpack .../systemd_237-3ubuntu10.43_i386.deb ...
Unpacking systemd (237-3ubuntu10.43) over (237-3ubuntu10.42) ...
Preparing to unpack .../libsystemd0_237-3ubuntu10.43_i386.deb ...
Unpacking libsystemd0:i386 (237-3ubuntu10.43) over (237-3ubuntu10.42) ...
Setting up libsystemd0:i386 (237-3ubuntu10.43) ...
Setting up systemd (237-3ubuntu10.43) ...
Setting up libnss-systemd:i386 (237-3ubuntu10.43) ...
Setting up libpam-systemd:i386 (237-3ubuntu10.43) ...
Processing triggers for libc-bin (2.27-3ubuntu1.4) ...
Processing triggers for man-db (2.8.3-2ubuntu0.1) ...
Processing triggers for dbus (1.12.2-1ubuntu1.2) ...
Processing triggers for ureadahead (0.100.0-21) ...
Log ended: 2021-01-07 13:29:10

... this even though the (ssh) interface died at the point where systemd was being set up. The system now runs systemd 237-3ubuntu10.43. But based on past experience I think the same thing will happen the next time there is a version upgrade of systemd.