mq: fix queue.apply to not call os.chdir() call to os.chdir broke "hg -R dirname qpush". instead pass -d (change directory) option to patch command.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m test -d "1000000 0"
hg history
hg manifest
hg cat a
hg verify