Fix special case if addon product is now set to require a voucher (vouchers for addons are not supported)

src/pretix/base/services/orders.py

@@ -2104,8 +2104,8 @@ class OrderChangeManager:
         def _addon_is_available(a):
             # If an item is no longer available due to time, it should usually also be no longer
             # user-removable, because e.g. the stock has already been ordered.
-            # We always set has_voucher=True because if a product now requires a voucher, it usually does
-            # not mean it should be unremovable for others.
+            # We always set voucher=None because that's what's done when generating the form in
+            # OrderChangeMixin (vouchers for addons are not supported).
             # This also prevents accidental removal through the UI because a hidden product will no longer
             # be part of the input.
             if not _allowed_on_order_sales_channel(a.item, self.order) or (
@@ -2117,7 +2117,7 @@ class OrderChangeManager:
                 self.order.event,
                 channel=self.order.sales_channel,
                 subevent=a.subevent,
-                has_voucher=True,
+                voucher=None,
                 base_qs=Item.objects.filter(pk=a.item.pk),
                 allow_addons=True
             )

src/pretix/presale/productlist.py

@@ -57,7 +57,7 @@ def item_group_by_category(items):
 def prepare_item_list_for_shop(event, *, channel: SalesChannel, subevent=None, voucher=None, require_seat=0, base_qs=None,
                                allow_addons=False, allow_cross_sell=False,
                                quota_cache=None, filter_items=None, filter_categories=None, memberships=None,
-                               ignore_hide_sold_out_for_item_ids=None, has_voucher=False):
+                               ignore_hide_sold_out_for_item_ids=None):
     base_qs_set = base_qs is not None
     base_qs = base_qs if base_qs is not None else event.items
 
@@ -74,7 +74,7 @@ def prepare_item_list_for_shop(event, *, channel: SalesChannel, subevent=None, v
         Q(Q(available_from__isnull=True) | Q(available_from__lte=time_machine_now()) | Q(available_from_mode='info')) &
         Q(Q(available_until__isnull=True) | Q(available_until__gte=time_machine_now()) | Q(available_until_mode='info'))
     )
-    if not has_voucher and (not voucher or not voucher.show_hidden_items):
+    if not voucher or not voucher.show_hidden_items:
         variation_q &= Q(hide_without_voucher=False)
 
     if memberships is not None: