Resolved two more edge cases in quota handling

Scenario 1) Blocking voucher is used in a CartPosition. Previously
too much was subtracted from the quota.

Scenario 2) When two quotas are assigned to a product and one of them
is sold out, blocking vouchers for the other quota should not enable to
buy the product.

src/pretix/base/models/items.py

@@ -554,6 +554,10 @@ class Quota(LoggedModel):
 
         return CartPosition.objects.filter(
             Q(expires__gte=now()) &
+            ~Q(
+                Q(voucher__isnull=False) & Q(voucher__block_quota=True)
+                & Q(Q(voucher__valid_until__isnull=True) | Q(voucher__valid_until__gte=now()))
+            ) &
             self._position_lookup
         ).distinct().count()
 

src/pretix/base/services/orders.py

@@ -222,8 +222,13 @@ def _check_positions(event: Event, dt: datetime, positions: List[CartPosition]):
 
         quota_ok = True
 
-        if not cp.voucher or not (cp.voucher.allow_ignore_quota or cp.voucher.block_quota):
+        ignore_all_quotas = cp.expires >= dt or (
+            cp.voucher and (cp.voucher.allow_ignore_quota or (cp.voucher.block_quota and cp.voucher.quota is None)))
+
+        if not ignore_all_quotas:
             for quota in quotas:
+                if cp.voucher and cp.voucher.block_quota and cp.voucher.quota_id == quota.pk:
+                    continue
                 avail = quota.availability()
                 if avail[0] != Quota.AVAILABILITY_OK:
                     # This quota is sold out/currently unavailable, so do not sell this at all