(maint) Fix old acceptance test refspec issue

The old refspec for acceptance testing source code only really worked for the
PR testing workflow. This patch makes it work for the command line or polling
based workflow as well.

Without it, it makes it hard to run beaker acceptance tests from the command
line.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #1038 from kbarber/maint/master/fix-accetpance-refspec-issue

(maint) Fix old acceptance test refspec issue