Currently, one could think that 'git bundle create' groks
any 'git rev-list' expression. But in fact it requires a named reference
to be present. Try and make this clearer.
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net> Acked-by: Thomas Rast <trast@student.ethz.ch> Signed-off-by: Junio C Hamano <gitster@pobox.com>