The current runner code is only able to handle one arch at a time. While this makes sense logically, it does cause a bit of a problem for repo-creating (and possibly multi-arch) tasks like depcheck.

With the current code, there is no way to specify multiple arches - even 'x86_64 and noarch'. The command line only accepts one value and the advertised 'all' arch does not work. Even if the argparse code is changed, the yaml rendering code can't seem to handle a list of options without blowing out the stack due to recursion.

The solution I propose is this:

• change the argparse code to allow multiple values for --arch
• render the arches as CSV
• split the CSV values inside koji_directive to create a list of arch strings

This is somewhat related to #155 but covers the "use i686 and x86_64" use case instead of just adding noarch to downloads (assuming that is the solution chosen)