> I've rerun kvm_mkdb, etc;

You have to delete /var/db/kvm.db, because kvm_mkdb is BUGGY.

I have just determined that the string stored as the VRS_KEY in /var/db/kvm.db
has zero length (at least on my system here), which causes it to compare
"equal" to whatever string (isn't) read out of /netbsd.

The code in nlist_aout.c (at least) must be calculating the offset incorrectly,
because it is reading in a string which starts with a NUL byte.

I don't know a.out format well enough to spot the problem by inspection.
If no one has found the problem by inspection by tonight, I'll look at it
more carefully when I have time.