Have you tried searching the archives on
www.insecure.org? They have archives of their mailing lists. If you're sure you've found a real bug, post it to the nmap-dev mailing list.
By the way, why in the world are you compiling nmap from source on OpenBSD? There is a very actively maintained port of nmap in /usr/ports/(security|net)/nmap (I forget which sub directory in ports). I personally know the port maintainer and he usually gets the new version in the -current ports tree within a few days of source release.
