item: check id and parent instead of url in test_Item_getTrackingList_explanation_brain_attribute

Since 8a6c4394 Item_getTrackingList sets
parent and id on brain instead of url.

testItem now passes: https://nexedijs.erp5.net/#/test_result_module/20190625-614B59A1

/reviewed-on nexedi/erp5!898

product/ERP5/tests/testItem.py

@@ -1114,7 +1114,8 @@ class TestItemScripts(ERP5TypeTestCase):
     self.assertEqual('explanation title', history_item.explanation)
     self.assertEqual('Sale Packing List Line', history_item.translated_portal_type)
     self.assertEqual(1, history_item.quantity)
-    self.assertEqual(line.absolute_url(), history_item.url)
+    self.assertEqual(line.getId(), history_item.getId())
+    self.assertEqual(line.getParentValue(), history_item.getParentValue())
     self.assertEqual((), history_item.variation_category_item_list)
     self.assertEqual('Delivered', history_item.simulation_state)