skip tb_next initalization

Author: youknowone

Lib/unittest/result.py

@@ -233,8 +233,9 @@ def _remove_unittest_tb_frames(self, tb):
         while tb and not self._is_relevant_tb_level(tb):
             prev = tb
             tb = tb.tb_next
-        if prev is not None:
-            prev.tb_next = None
+        # TODO: RUSTPYTHON; traceback.tb_next is not writable yet #3857
+        # if prev is not None:
+        #     prev.tb_next = None
 
     def __repr__(self):
         return ("<%s run=%i errors=%i failures=%i>" %