git-bundle: die if a given ref is not included in bundle

git-bundle: die if a given ref is not included in bundle

The earlier patch tried to be nice by just warning, but it seems
more likely that the user wants to adjust the parameters.

Also, it prevents a bundle containing _all_ revisions in the case
when the user only gave one ref, but also rev-list options which
excluded the ref.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>