pretend_min_part_hours_passed do things like this: self._last_part_moves[part] = 0xff this will throw exception if self._last_part_moves is None. this patch is to check self._last_part_moves to prevent exception. Closes-bug: #1578835 Change-Id: Ic83c7a338b45bfcf61f5ab6100e6db335c3fa81a