deleting the terminal prompt?

[MackS]

Dear all,

I just noticed the following behavior when I run

import os
import sys
import readline

histfile = os.path.join(os.environ["HOME"], ".pyhist")

try:
    readline.read_history_file(histfile)
except IOError:
    pass

import atexit
atexit.register(readline.write_history_file, histfile)
del os, histfile

while cmd != "":

    sys.stdout.write("prompt: ")
    cmd = raw_input()

    # at this point it studies the contents of cmd and decides what to
do next.

However, if the user simply presses Tab followed by a backspace  s/he
effectively makes the prompt disappear. Is there a way to prevent this
from happening?


Thanks for any help,

Mack