sysutils/screen compilation oddities on stable-14

Hi,

I'm running a somewhat recent stable-14/amd64 (refreshed 27-Dec-2023), 
and I wonder if someone can explain what is happening...

I've got a dev-host which I use as a repo-builder. I have discovered 
that if I have linux_enable="YES" on the repo-builder, the resultant 
executable from the sysutils/screen package produced will only behave as 
expected on other hosts that also have linux_enable="YES". On hosts 
where linux_enable is *not* defined (ie linux_enable="NO"), `screen' 
will start up and then immediatly quit. There are no core-dumps, or any 
other noticeable error-messages.

If I set linux_enable="NO" on the repo-builder, the executable from the 
sysutils/screen package produced will work as expected on _all_ hosts, 
ie linux_enable=YES|NO.

Can someone explain why this is so?

Cheers.
-- 
Jonathan Chen <jonc@chen.org.nz>