The response from the rpm list seems to indicate that the problem I am having is an rpm bug in versions < 3.04, and the response on how to get around the bug was "upgrade to 3.04". Rather than require that rpm be a certain version, I am going to remove this option. Anyone who wishes to build under a different architecture than the default can still make a source RPM with Distutils and then run `rpm -bb` from the command line.
I am currently adding CFLAGS support so that the i686 and i586 RPMs generated by default on Pentium-class machines will really be i686 and i586 RPMs