tests/test-hgk

setup: use sys.executable to call hg

Executing ".\hg" does not work on Windows, but we can instead ask
Python to execute hg.

#!/bin/sh

echo "[extensions]" >> $HGRCPATH
echo "hgk=" >> $HGRCPATH

hg init repo
cd repo
echo a > a
hg ci -Am adda
hg debug-cat-file commit 0