[ossec-list] trouble upgrading client

[Jeff Dyke]

I've had ossec-hids-agent and server installed for well over a year,
perhaps two. Today a new package hit Ubuntu's 18.04 repository and it
would not update, the errors follow, unfortunately there is no helpful
information in /var/log/dpkg.log. Just says that its running the 'update'
command.
---- Console output ---
Preparing to unpack .../ossec-hids-agent_3.1.0-5711bionic_amd64.deb ...
prerm called with unknown argument `upgrade'
dpkg: warning: old ossec-hids-agent package pre-removal script subprocess
returned error exit status 1
dpkg: trying script from the new package instead ...
prerm called with unknown argument `failed-upgrade'
dpkg: error processing archive
/var/cache/apt/archives/ossec-hids-agent_3.1.0-5711bionic_amd64.deb
(--unpack):
new ossec-hids-agent package pre-removal script subprocess returned error
exit status 1
Errors were encountered while processing:
/var/cache/apt/archives/ossec-hids-agent_3.1.0-5711bionic_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
--- End Output ---
I've not run into this too much, so if this is general and not specific to
a package, any pointers are helpful, otherwise, hopefully this will help
the maintainer update the package.

Best,
Jeff