With the fix below is becomes possible to build rpms on the Mac.

The developer will need to install rpm tooling.  That's easy via "brew install rpm".

That, for example, installs /usr/local/bin/rpmbuild.

Sadly bdist_rpm.py only supports rpmbuild in two places, see:

https://github.com/python/cpython/blob/6f0eb93183519024cb360162bdd81b9faec97ba6/Lib/distutils/command/bdist_rpm.py#L313

Which due to the Mac's fastidious security setup we are very strongly discouraged from working around.

So, yeah, let's add a third, like so maybe:

        if ((os.path.exists('/usr/bin/rpmbuild')
             or os.path.exists('/bin/rpmbuild')
             or os.path.exists('/usr/local/bin/rpmbuild'))):
            rpm_cmd = ['rpmbuild']

And now I can use build_rpm on my mac, oh joy.