I'm worried that this local variable assigment (and the ones below) will create refleaks, because the traceback holds a reference to the framestack[1].  I think we need to two two things:

- Avoid unpacking the 'exc_info' into three extra variables.

- Capture 'exc_info' outside the current 'try:' block, but inside another one which has a 'finally:' which does 'del exc_info'

[1] http://docs.python.org/2/library/sys.html#sys.exc_info