sudo dumping core on recent current

Kia ora,
I'm running 11.99.4 on a couple of amd64 systems and after I upgraded 
pkgsrc on them I noticed that sudo now dumps core whenever I run it as 
an unprivileged user.

I have tried sudo-1.9.17p1 from pkgsrc built and run on a very recent 
copy of -current and it always dumps core when I run "sudo ls". I have 
tried building it with the system GCC 14 and the pkgsrc GCC 13 with no 
change in behaviour.

I have tried sudo-1.9.17p1 from pkgsrc built on a slightly older version 
of 11.99.4 and that seems to work on older and newer 11.99.4 systems.

I have no idea how to debug this because sudo won't dump an actual core 
file if it's setuid root and won't run if it isn't.

I also don't have the wherewithall needed to cope with CVS' inability to 
tell me exactly which version of the source tree I have in any given 
checkout. I don't normally do an "update" build, so I don't think I'm 
not hitting the recent pthread change.

If anyone can give me some advice on how to move forwards, I would be 
grateful.

Ngā mihi,
Lloyd