budget consumption report: display 0 instead of NaN when there's no budget

bt5/erp5_budget/SkinTemplateItem/portal_skins/erp5_budget/Budget_getBudgetConsumptionReportData.xml

@@ -291,7 +291,7 @@ for budget in budget_list:\n
           if not engaged_budget:\n
             engaged_budget = 0\n
 \n
-          initial_budget = None\n
+          initial_budget = 0\n
           if cell is not None:\n
             initial_budget = cell.getQuantity() * sign\n
 \n

bt5/erp5_budget/bt/revision

-379
+380
\ No newline at end of file