diff -r 273e17260d25 Lib/multiprocessing/managers.py
--- a/Lib/multiprocessing/managers.py	Thu Apr 10 09:29:39 2014 -0400
+++ b/Lib/multiprocessing/managers.py	Fri Apr 11 19:17:29 2014 +0200
@@ -275,7 +275,7 @@
                 try:
                     send(msg)
                 except Exception as e:
-                    send(('#UNSERIALIZABLE', repr(msg)))
+                    send(('#UNSERIALIZABLE', format_exc()))
             except Exception as e:
                 util.info('exception in thread serving %r',
                         threading.current_thread().name)