Port needs a fix indentical to the https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=243387 for obvious reasons.
I've just hit the problem by installing dns/samba-nsupdate from Ports.
Since I'm unable to apply the fix by myself, I've Cc'd a few guys to kindly ask them to do the same magic they did with bug #243387 ... thanks! :)
Created attachment 215691 [details]
I found that updating the dependency from BIND 9.14.2 to BIND 9.16.3 seems to solve the issue. Here is the patch for it.
Just like in the previous comment, updating the dependency to BIND 9.16.5 (the latest for now), fixes the problem as well.
Perhaps it makes sense to track the latest ISC BIND version, just like dns/bind-tools port does?