forked from CGM_Public/pretix_original
* Fix crash in rebooking if addon has hidden_if_item_available * Move get_grouped_items into its own file and rename to prepare_item_list_for_shop (but keep a reference under original name for plugin compatibility) * Make Item[Variation].unavailability_reason helper functions next to get_grouped_items * Use current_unavailability_reason attribute instead of unavailability_reason() * Add test case for: Order has product with addon 1; Addon 1 is hidden if Addon 2 is available; When order is changed, Addon 1 should not be removable * Fix special case if addon product is now set to require a voucher (vouchers for addons are not supported) --------- Co-authored-by: Kara Engelhardt <engelhardt@pretix.eu>