This is a quasi limitation on the way the arch chroot build system works. When you issue your build command, the chroot is always updated to the latest sources/versions before building (insures built packages run on arch), but does NOT insure packages run on virtualized versions of arch that rely on 3rd party drivers that may not be updated to the latest sources/versions :(
So people using Arch WILL update to bleeding edge whether or not they want? No thanks!
On the positive NOTE -> my automated build ran from start to stop without a hiccup :)
:)
Darrell