Fix problem introduced in r31762 : Supply Line need Reference property sheet

and it has been removed by removing DeliveryLine from SupplyLine inheritance.
Tests has been added in r32616 and r32618

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@32668 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/SupplyLine.py

@@ -63,6 +63,7 @@ class SupplyLine(Path, XMLMatrix):
                       , PropertySheet.FlowCapacity
                       , PropertySheet.Predicate
                       , PropertySheet.Comment
+                      , PropertySheet.Reference
                       )
 
     #############################################