[arch-releng] pacman.conf.{i686,x86_64} ignored by archiso?

in the releng env (http://projects.archlinux.org/users/dieter/releng.git/tree/) it seems the pacman.conf.{i686,x86_64} files are now being ignored. (i enabled testing in there but it's not used) Frankly I don't even know/remember how this ever worked, I can't find a reference to these files anywhere. How does one control which pacman.conf archiso must use during building of the arch environment it puts on the isos? Dieter