tinderbox and bad system call

After upgrading tinderbox's jail to latest -current,
miwi_at_ and I see this "bad system call (core dumped)"
while building devel/glib20. My log is at

http://www.rafan.org/tb/errors/7-FreeBSD/glib-2.12.12_2.log

My tinderbox is running on 6.2-RELEASE. Not sure about
miwi_at_'s but I think they are 6.x. I think it's related to recent
changes in current and may only happen in tinderbox environment.

Any ideas?

Regards,
Rong-En Fan