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
HGRCPATH=$HGTMP/.hgrc; export HGRCPATH
echo "[extensions]" >> $HGTMP/.hgrc
echo "mq=" >> $HGTMP/.hgrc
hg init foo
cd foo
echo foo > foo
hg add foo
# mq may keep a reference to the repository so __del__ will not be called
# and .hg/journal.dirstate will not be deleted:
HGEDITOR=false hg ci
HGEDITOR=false hg ci
exit 0