In python 3 the behavior of sys.exc_info had a very subtle change:

- in python 2 you can call if whenever you want after a try/except statement
  and you'll get information about this last raise
- ipython 3, once you get out of try/except, sys.exc_info is cleaned and you'll
  get (None, None, None)

Hardened the test to avoid this error from happening again.