Run commit message editor in the repo root (like hooks).
This makes the hgeditor script work with hg commit -R path/to/repo
#!/bin/sh
hg init
cat > .hg/hgrc <<EOF
[encode]
*.gz = gunzip
[decode]
*.gz = gzip
EOF
echo "this is a test" | gzip > a.gz
hg add a.gz
hg ci -m "test" -d "0 0"
echo %% no changes
hg status
touch a.gz
echo %% no changes
hg status
echo %% uncompressed contents in repo
hg debugdata .hg/data/a.gz.d 0
echo %% uncompress our working dir copy
gunzip < a.gz
rm a.gz
hg co
echo %% uncompress our new working dir copy
gunzip < a.gz