Well, I am not really a Debian guy, i.e., I use the whole dpkg stuff to build my packages, which seems to work out quite well for the time being, but I am far from being in expert with respect to Debian packaging.
Still, I suspect this to be normal behavior.

I think at the time you performed the update the prerm script of the old version, which still contained the bug, had been used.
Hence, you experience this issue.
But since you now have the new version installed, with the fixed prerm script, from now on this problem should not occur anymore.

Edit:
With respect to all the issues and requests reported recently: I am currently very very busy.
So I cannot invest that much, if any, time into this right now.
Though, I think all this stuff will be taken care of sooner or (most probably) later.