check the value of the old quantity

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@4682 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/TargetSolver/CopyToTarget.py

@@ -49,6 +49,8 @@ class CopyToTarget(TargetSolver):
     new_start_date = movement.getDeliveryStartDateList()[0]
     new_stop_date = movement.getDeliveryStopDateList()[0]
     # Calculate delta
+    quantity_ratio = 0
+    if old_quantity not in (None,0.0):
       quantity_ratio = new_quantity / old_quantity
     start_date_delta = 0
     stop_date_delta = 0