by reading this I just learned about the concept of chained exceptions, although I can't see why is so useful, the built-in traceback and sys module has always been good enough:

    import sys,traceback
    try:
        ...
    except Exception as ex:
        exc_type, exc_value, exc_traceback = sys.exc_info()
        logger.error("%s:%s" % (str(ex),  str(traceback.format_exception(exc_type, exc_value, exc_traceback))))
        raise MyException(" :( ")