Use Py_CLEAR instead of in-place DECREF/XDECREF or custom macros, for
tp_clear methods.
diff --git a/Python/traceback.c b/Python/traceback.c
index 567f23d..cdbec2b 100644
--- a/Python/traceback.c
+++ b/Python/traceback.c
@@ -53,10 +53,8 @@
 static void
 tb_clear(PyTracebackObject *tb)
 {
-	Py_XDECREF(tb->tb_next);
-	Py_XDECREF(tb->tb_frame);
-	tb->tb_next = NULL;
-	tb->tb_frame = NULL;
+	Py_CLEAR(tb->tb_next);
+	Py_CLEAR(tb->tb_frame);
 }
 
 PyTypeObject PyTraceBack_Type = {