erp5_base: BuilderMixin add Missing Initialization for a variable

bt5/erp5_base/MixinTemplateItem/portal_components/mixin.erp5.BuilderMixin.py

@@ -529,6 +529,7 @@ class BuilderMixin(XMLObject, Amount, Predicate):
     original_order_quantity_unit_value = supply.getOrderQuantityUnitValue()
     original_batch_order_quantity = supply.getBatchOrderQuantity()
     # Create a movement per period
+    next_next_period_start_date = None
     for period_start_date in limit_date_list:
       # Prepare history list of the current period
       next_period_start_date = DateTime(supply.getNextPeriodicalDate(