purge extension doesn't need "#!/usr/bin/env python".
(from the Debian package: deb_specific__hgpurge.py.patch)
#!/bin/sh
hg init a
cd a
echo a > foo
hg rm foo
hg add foo
hg commit -m 1 -d "1000000 0"
hg remove
rm foo
hg remove foo
hg revert --all
rm foo
hg remove --after
hg commit -m 2 -d "1000000 0"
hg export --nodates 0
hg export --nodates 1
hg log -p -r 0
hg log -p -r 1
echo a > a
hg add a
hg rm a
hg rm -f a
echo b > b
hg ci -A -m 3 -d "1000001 0"
echo c >> b
hg rm b
hg rm -f b
cd ..
hg clone a b