`git rev-list --max-count=1 HEAD` is a roundabout way of saying `git
rev-parse --verify HEAD`; replace a bunch of instances of the former
with the latter. Also, don't unnecessarily `cut -c1-7` the rev-parse
output when the `--short` option is available.
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>