new extension: fetch -> combine pull and merge/update pull changes from remote repo. if changes add new head: merge with new head, commit result. else: update working dir to new head. this makes useful command like git 'pull' command.

#!/bin/sh

mkdir a
cd a
hg init
echo foo > b
hg add b
hg ci -m "b" -d "1000000 0"

chmod -w .hg

cd ..

hg clone a b

chmod +w a/.hg # let test clean up

cd b
hg verify