Removing package leaves motd script in place, renders incorrect motd

[panlinux]

From https://bugs.launchpad.net/ubuntu/+source/ubuntu-advantage-tools/+bug/1707290:

Removing the ubuntu-advantage-tools package (not purging: removing) will leave the /etc/update-motd.d/99-esm script in place. Accordingly, it will run at login time, but since it calls out to the ubuntu-advantage script that no longer exists, it fails.

This is the sequence of events:

• ubuntu-advantage-tools is installed
• sudo ubuntu-advantage enable-esm with a valid token is run
• logout and login, confirming that the MOTD says something like "This Ubuntu 12.04 system is configured to receive extended security updates"
• remove (not purge) the ubuntu-advantage package. This will leave the sources.list.d/ file with the ESM repository in place and working, and the MOTD script, but remove the ubuntu-advantage script
• logout and login. The MOTD will now say "This Ubuntu 12.04 LTS system is past its End of Life", even though the ESM repository is still enabled and functioning.