Thanks for your reply to my message.
This is WAG, but did/do you have PKG_CACHE defined?
I've never set it explicitly, and it isn't defined on either system.
$ env | grep PKG
PKG_PATH=ftp://openbsd.mirror.frontiernet.net/pub/OpenBSD/4.5/packages/i386
$
Locate on the upgraded (borked) system doesn't turn up anything that looks
like a package to me
$ locate gv-3
/usr/local/share/doc/gv/gv-3.html
/var/db/pkg/gv-3.5.8p4
/var/db/pkg/gv-3.5.8p4/+CONTENTS
/var/db/pkg/gv-3.5.8p4/+DESC
/var/db/pkg/gv-3.5.8p4/+REQUIRING
$
The upgraded system has a ports tree, which, now that I think about it,
hasn't been upgraded. But it's my understanding that packages work
independently of any port tree that may be installed locally.