Thank you to all who responded in this thread and by private email -- your replies were very helpful! Following Stuart Henderson's suggestion, I found that I did indeed have a /usr/local/libdata/perl5/site_perl/amd64-openbsd/auto/Term/ReadLine/Gnu containing (among other things) an out-of-date file Gnu.so.
I have now "solved" the problem by replacing the entire /usr/local/libdata/perl5/ tree with a copy of that from a twin machine (also amd64/7.3, just upgraded from 7.2) which doesn't seem to have this problem. After that the immediate problem (fatal error on /use Term::ReadPassword;/) is gone. I did another full 'pkg_add -uvv' to be on the safe side, which found a few 'file already exists', but after overwriting those everything seems to be working now. Thanks again to everyone who helped! ciao, -- -- "Jonathan Thornburg [remove -color to reply]" <dr.j.thornb...@gmail-pink.com> on the west coast of Canada "Now back when I worked in banking, if someone went to Barclays, pretended to be me, borrowed UKP10,000 and legged it, that was `impersonation', and it was the bank's money that had been stolen, not my identity. How did things change?" -- Ross Anderson