contrib/subtree: ensure only one rev is provided
While looking at the inline help for git-subtree.sh, I noticed that
git subtree split --prefix=<prefix> <commit...>
was given as an option. However, it only really makes sense to provide
one revision because of the way the commits are forwarded to rev-parse
so change "<commit...>" to "<commit>" to reflect this. In addition,
check the arguments to ensure that only one rev is provided for all
subcommands that accept a commit.
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Acked-by: Avery Pennarun <apenwarr@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>