[FIX][trunk] stock - Error in new company

bzr revid: hip@tinyerp.com-20121212062932-aijgsk27m0sl1qv5

addons/stock/product.py

@@ -235,6 +235,8 @@ class product_product(osv.osv):
         else:
             location_ids = []
             wids = warehouse_obj.search(cr, uid, [], context=context)
+            if not wids:
+                return res
             for w in warehouse_obj.browse(cr, uid, wids, context=context):
                 location_ids.append(w.lot_stock_id.id)