Fix shifts creation bug if non-recurrent shift_template exist in database

intercoop_addons/coop_shift/model/shift_template.py

@@ -578,6 +578,8 @@ class ShiftTemplate(models.Model):
             before = fields.Datetime.to_string(
                 datetime.today() + timedelta(days=SHIFT_CREATION_DAYS))
         for template in self:
+            if len(str(template.rrule).strip()) == 0:
+                continue  # It's not a recurring template
             after = template.last_shift_date
             rec_dates = template.get_recurrent_dates(
                 after=after, before=before)