Fix for wmf_civicrm_mark_refund

Zero is a valid count with a rowcount of 1.
The very next "if" always errors.

Change-Id: I5fd86c0b74688d3e29b9752c101124b2d20497dc
Merge remote-tracking branch 'origin/master' into HEAD

* Fix for wmf_civicrm_mark_refund

Change-Id: Ic0f157ffd4b29eb0d164e260ce55edd235743b2e