#78 Ocasional hangup

This has only happened 2 times, once while on NetBSD using tmux(1) while compiling some stuff and another time on my work Macbook just doing an isearch.

On NetBSD it would happen when I tried to save -- this is likely due to the backup but there isn't any evidence for that exactly, just a thought.

On Mac, I have no idea.

Steps to reproduce:

1. open file using scripts/ff (i.e. aitff``)
2. isearch for something that isn't found
3. backspace a few times

ait will hang. C-g won't work and you'll have to kill it manually.