Do not copy cached amounts of sale, purchase and purchase requisition

Closes #13336

modules/purchase/purchase.py

@@ -724,6 +724,9 @@ class Purchase(
         default.setdefault('purchase_date', None)
         default.setdefault('quoted_by')
         default.setdefault('confirmed_by')
+        default.setdefault('untaxed_amount_cache')
+        default.setdefault('tax_amount_cache')
+        default.setdefault('total_amount_cache')
         return super(Purchase, cls).copy(purchases, default=default)
 
     def check_for_quotation(self):

modules/purchase_requisition/purchase.py

@@ -332,6 +332,7 @@ class PurchaseRequisition(Workflow, ModelSQL, ModelView):
         default.setdefault('supply_date', None)
         default.setdefault('approved_by')
         default.setdefault('rejected_by')
+        default.setdefault('total_amount_cache')
         return super(PurchaseRequisition, cls).copy(
             requisitions, default=default)
 

modules/sale/sale.py

@@ -808,6 +808,9 @@ class Sale(
         default.setdefault('sale_date', None)
         default.setdefault('quoted_by')
         default.setdefault('confirmed_by')
+        default.setdefault('untaxed_amount_cache')
+        default.setdefault('tax_amount_cache')
+        default.setdefault('total_amount_cache')
         return super(Sale, cls).copy(sales, default=default)
 
     def check_for_quotation(self):