exc.py: Changed to store multiple tracebacks in an exception, in case an exception is caught and re-raised inside an ExceptionWithCause wrapper. This preserves more of the traceback in this situation, because you get the ExceptionWithCause's traceback as well.
exc.py: Changed to store multiple tracebacks in an exception, in case an exception is caught and re-raised inside an ExceptionWithCause wrapper. This preserves more of the traceback in this situation, because you get the ExceptionWithCause's traceback as well.