Using rpmbuild -ta with nightly CVS snapshots

[Philip Prindeville <philipp_subx redfish-solutions com>]

I'm trying to use a simple cron script to grab the nightly CVS tarball 
from a project and do an "rpmbuild -ta" on it to ensure that no one has 
checked in code that either breaks the .spec file or hasn't been built 
on multiple platforms (I run this script on a farm).

Unfortunately, the script fails because %{SOURCE0} isn't being set to 
the argument passed into rpmbuild -ta ...

Shouldn't the behavior of "rpmbuild -t..." be to ignore SOURCE0 and use 
the tarball from the command line???