I discovered a rather nasty side effect of the standard
cmd.py library
today. If it's sitting inside raw_input(), any SIGCLDs
that get sent to
your application get silently eaten and ignored. I'm
assuming that this
is something that readline is thoughtfully doing for me.

This patch adds an instance attr that allows the user
to select to
not use raw_input(), but instead use sys.stdin.readline()