simplify make_filename, fix hg cat bug hg cat was using file-level rev/node ids for generating filename templates. This simplifies make_filename to only use changeset rev/node ids.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m "test" -d "1000000 0"
hg verify
hg parents
hg status
hg rollback
hg verify
hg parents
hg status