tests/test-hup

Enable path validation for copy, rename, debugwalk and other canonpath users.
This fixed the last bit of issue134.
Added some tests to test-rename and test-walk.

#!/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