Comment 36 for bug 1881632

And finally successful xenial results (which required dropping xenial-updates and xenial-security from apt sources because those pockets contain a greater pkg version than what esm currently delivers for libkrad0.

--- BEGIN xenial update-notifier testing
--- Launch cloud-init with ppa:ua-client/proposed enabled
Creating test-sru-xenial
Starting test-sru-xenial
--- Wait for cloud-init to finish
.......................................................................
status: done
time: Sun, 27 Dec 2020 21:46:17 +0000
detail:
DataSourceNoCloud [seed=/var/lib/cloud/seed/nocloud-net][dsmode=net]
--- Attach Ubuntu-Advantage, enabling services
Enabling default service esm-infra
Updating package lists
ESM Infra enabled
This machine is now attached to '<email address hidden>'

SERVICE ENTITLED STATUS DESCRIPTION
esm-infra yes enabled UA Infra: Extended Security Maintenance (ESM)
livepatch yes n/a Canonical Livepatch service

Enable services with: ua enable <service>

     Account: <email address hidden>
Subscription: <email address hidden>
-- Downgrading package to stable ubuntu release libkrad0=1.13.2+dfsg-5
Reading package lists...
Building dependency tree...
Reading state information...
The following package was automatically installed and is no longer required:
  libfreetype6
Use 'apt autoremove' to remove it.
The following additional packages will be installed:
  libverto-libevent1 libverto1
The following NEW packages will be installed:
  libkrad0 libverto-libevent1 libverto1
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 36.1 kB of archives.
After this operation, 207 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu xenial/main amd64 libverto-libevent1 amd64 0.2.4-2.1ubuntu2 [5742 B]
Get:2 http://archive.ubuntu.com/ubuntu xenial/main amd64 libverto1 amd64 0.2.4-2.1ubuntu2 [9132 B]
Get:3 http://archive.ubuntu.com/ubuntu xenial/main amd64 libkrad0 amd64 1.13.2+dfsg-5 [21.3 kB]
Fetched 36.1 kB in 0s (49.7 kB/s)
Selecting previously unselected package libverto-libevent1:amd64.
(Reading database ... 25866 files and directories currently installed.)
Preparing to unpack .../libverto-libevent1_0.2.4-2.1ubuntu2_amd64.deb ...
Unpacking libverto-libevent1:amd64 (0.2.4-2.1ubuntu2) ...
Selecting previously unselected package libverto1:amd64.
Preparing to unpack .../libverto1_0.2.4-2.1ubuntu2_amd64.deb ...
Unpacking libverto1:amd64 (0.2.4-2.1ubuntu2) ...
Selecting previously unselected package libkrad0:amd64.
Preparing to unpack .../libkrad0_1.13.2+dfsg-5_amd64.deb ...
Unpacking libkrad0:amd64 (1.13.2+dfsg-5) ...
Processing triggers for libc-bin (2.23-0ubuntu11.2) ...
Setting up libverto-libevent1:amd64 (0.2.4-2.1ubuntu2) ...
Setting up libverto1:amd64 (0.2.4-2.1ubuntu2) ...
Setting up libkrad0:amd64 (1.13.2+dfsg-5) ...
Processing triggers for libc-bin (2.23-0ubuntu11.2) ...
update-notifier
Hit:1 http://archive.ubuntu.com/ubuntu xenial InRelease
Hit:2 http://ppa.launchpad.net/ua-client/staging/ubuntu xenial InRelease
Hit:3 http://archive.ubuntu.com/ubuntu xenial-backports InRelease
Get:4 https://esm.ubuntu.com/infra/ubuntu xenial-infra-security InRelease [7458 B]
Hit:4 https://esm.ubuntu.com/infra/ubuntu xenial-infra-security InRelease
Get:5 https://esm.ubuntu.com/infra/ubuntu xenial-infra-updates InRelease [7457 B]
Hit:5 https://esm.ubuntu.com/infra/ubuntu xenial-infra-updates InRelease
Reading package lists... Done
2 packages can be updated. 0 updates are security updates.
SUCCESS: did not find UA Infra: Extended Security Maintenance (ESM) is enabled
SUCCESS: found 0 updates are security updates security updates pre-upgrade
--- Upgrade update-notifier from -proposed
  update-notifier-common
Get:1 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 update-notifier-common all 3.168.13 [133 kB]
dpkg-preconfigure: unable to re-open stdin: No such file or directory
Preparing to unpack .../update-notifier-common_3.168.13_all.deb ...
Unpacking update-notifier-common (3.168.13) over (3.168.10) ...
Setting up update-notifier-common (3.168.13) ...
update-notifier
SUCCESS: found UA Infra: Extended Security Maintenance (ESM) is enabled
--- Expect non-zero upgradable packages for MOTD from apt_check AFTER upgrade
UA Infra: Extended Security Maintenance (ESM) is enabled.

6 packages can be updated.
1 of these updates is fixed through UA Infra: ESM.
1 of these updates is a security update.
To see these additional updates run: apt list --upgradable
1 of these updates is a security update.
SUCCESS: found 1 ESM security updates pre-upgrade