Comment 1 for bug 2012044

"I don't know where this variable oldver was passed in"
It is the version of the previous package installed. See:
https://www.debian.org/doc/debian-policy/ch-maintainerscripts.html#details-of-configuration

The post-install script can only know about the previous packaged version installed. Since the old version is from a source install, it's seeing the old version as nothing.

This is something that can potentially be modified, but in general I wouldn't recommend going from source install to package install. Is there a reason you can't start with a package install?

As a workaround, you can "rm /var/lib/cloud/data/upgraded-network".