Add issue8944.diff.

issue8944.diff

@@ -0,0 +1,17 @@
+--- a/trytond/trytond/modules/sale_shipment_cost/sale.py
++++ b/trytond/trytond/modules/sale_shipment_cost/sale.py
+@@ -168,13 +168,12 @@
+     def quote(cls, sales):
+         pool = Pool()
+         Line = pool.get('sale.line')
+-
+-        super(Sale, cls).quote(sales)
+         removed = []
+         for sale in sales:
+             removed.extend(sale.set_shipment_cost())
+         Line.delete(removed)
+         cls.save(sales)
++        super(Sale, cls).quote(sales)
+ 
+     @classmethod
+     @ModelView.button

series

@@ -59,3 +59,5 @@ issue9519.diff # [sale + purchase] Use search context for product field on line
 issue9814.diff #[product] Product template search bar showing non serchable product.product function fields as recomendation
 
 rule_account_journal_period.diff # [account] Add missing rule for account.journal.period
+
+issue8944.diff # [sale_shipment_cost] Prevent crash when duplicating a sale and moving it to quote state.