Index: Lib/unittest/case.py
===================================================================
--- Lib/unittest/case.py	(revision 84794)
+++ Lib/unittest/case.py	(working copy)
@@ -107,6 +107,12 @@
             expected_regexp = re.compile(expected_regexp)
         self.expected_regexp = expected_regexp
 
+def _clear_traceback(exc_value):
+    if isinstance(exc_value.__cause__, BaseException):
+        exc_value.__cause__ = _clear_traceback(exc_value.__cause__)
+    if isinstance(exc_value.__context__, BaseException):
+        exc_value.__context__ = _clear_traceback(exc_value.__context__)
+    return exc_value.with_traceback(None)
 
 class _AssertRaisesContext(_AssertRaisesBaseContext):
     """A context manager used to implement TestCase.assertRaises* methods."""
@@ -130,7 +136,7 @@
             # let unexpected exceptions pass through
             return False
         # store exception, without traceback, for later retrieval
-        self.exception = exc_value.with_traceback(None)
+        self.exception = _clear_traceback(exc_value)
         if self.expected_regexp is None:
             return True