Enhance the file filtering capabilities. We now allow filtering through either pipes or pairs of temporary files. The latter appear to be mandatory for use on Windows.

#!/bin/sh

hg init
mkfifo p

hg serve --stdio < p &
P=$!
(echo lock; echo addchangegroup; sleep 5) > p &
Q=$!
sleep 1
kill -HUP $P
sleep 1
ls .hg