Colin Watson wrote:
[...] Check that /etc/groff/man.local and /etc/groff/mdoc.local are in sync onthe two machines. You want the versions that look like this:
That was it. I must've missed an update to man.local during an upgrade. man.local.dpkg-dist was there, and I just copied it to man.local, and all is well now.
Thanks Colin! - Bob