to Doctest as SystemExit is to Python

[p.lavarre at ieee.org]

(((I thought I had sent this reply already, Google says No.)))

> > Can I somehow tell doctest that it's time to quit?
> > ... doctest redefines ... SystemExit ...
>
> Hit Ctrl-C. Or raise a KeyboardInterrupt:

Yes!  Thank you!!!  I see now,

Doctest exactly reverses the python -i experience:

        doctest exits quietly if I raise KeyboardInterrupt.
        doctest catches SystemExit and prints the traceback.

        python -i exits quietly if I raise SystemExit.
        python -i catches KeyboardInterrupt and prints the traceback.

Of course, to make the doctest work as sketched, I had to strip the
trailing blanks that my browser introduced and I had to expect
tracebacks for raise Exception and raise SystemExit, e.g.:

>>> import sys
>>> sys.exit()
Traceback (most recent call last):
  ...
SystemExit
>>>