Simple Fix Pushed to Master

[Tim Flink]

I pushed a quick fix to master (same code isn't in stable yet) that was
throwing exceptions if an arch wasn't specified for koji (which is the
default).

https://fedorahosted.org/autoqa/changeset/7a230188ed2926498ceac4a4061e267eb5...

I can't think of any problems this would cause but figured that I would
send out a quick email.

Tim