Fix a problem with path calculation when the level is lowering

lisp/org-taskjuggler.el

@@ -250,7 +250,8 @@ a path to the current task."
 	    (pop unique-ids)
 	    (pop path))
 	  (setq unique-id (org-taskjuggler-get-unique-id task (car unique-ids)))
-	  (push unique-id (car unique-ids))))
+	  (push unique-id (car unique-ids))
+	  (setcar path unique-id)))
 	(push (cons "unique-id" unique-id) task)
 	(push (cons "path" (mapconcat 'identity (reverse path) ".")) task)
 	(setq previous-level level)