Replying to my own message:

> This is with a kernel sup'ed about Wed Dec 23 20:15:17 MET 1998, and an old
> version (a few months) of Samba's smbd and nmbd running, and a certain network
> game on the local network running on some Windows 95 systems.

This had nothing to do with either smbd/nmbd nor the network game.
It's a typo in sys/net/route.c, I'm going to file a PR.


Martin