clone: provide sample username = config entry in .hg/hgrc (
issue4359)
Some users clone from a server before ever running 'hg config --edit',
so they don't see our helpful template for things like enabling the
username. Attempt to give them some helpful guidance.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qsave
$ hg qrestore 2
restoring status: hg patches saved state