Only add constr if event is not covered

AKModel/models.py

@@ -945,7 +945,7 @@ class AKSlot(models.Model):
 
         if self.fixed and self.start is not None:
             ak_time_constraints = [f"fixed-akslot-{self.id}"]
-        elif Availability.is_event_covered(self.event, self.ak.availabilities.all()):
+        elif not Availability.is_event_covered(self.event, self.ak.availabilities.all()):
             ak_time_constraints = [f"availability-ak-{self.ak.pk}"]
         else:
             ak_time_constraints = []