Comment 6 for bug 1888916

I tried this both with an Ubuntu desktop install of 18.04 LTS and an lxc cloud image of 18.04 LTS and during neither upgrade process did I encounter the error described in this bug report. Here's some relevant information from the lxc upgrade.

ubuntu@gorgeous-molly:~$ tail /var/log/dist-upgrade/screenlog.0

To finish the upgrade, a restart is required.
If you select 'y' the system will be restarted.

Continue [yN] y
W: molly-guard: SSH session detected!
Please type in hostname of the machine to reboot:
Good thing I asked; I won't reboot gorgeous-molly ...

=== Command detached from window (Tue Aug 4 03:29:45 2020) ===

ubuntu@gorgeous-molly:~$ cat /etc/apt/sources.list
## Note, this file is written by cloud-init on first boot of an instance
## modifications made here will not survive a re-bundle.
## if you wish to make changes you can:
## a.) add 'apt_preserve_sources_list: true' to /etc/cloud/cloud.cfg
## or do the same in user-data
## b.) add sources in /etc/apt/sources.list.d
## c.) make changes to template file /etc/cloud/templates/sources.list.tmpl

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://192.168.10.7/ubuntu focal main restricted
# deb-src http://192.168.10.7/ubuntu bionic main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://192.168.10.7/ubuntu focal-updates main restricted
# deb-src http://192.168.10.7/ubuntu bionic-updates main restricted
...