rebase: stricter check of standalone sub command

The sub commands '--continue', '--skip' or '--abort' may only be used
standalone according to the documentation. Other options following the
sub command are currently not accepted, but options preceeding them
are. For example, 'git rebase --continue -v' is not accepted, while
'git rebase -v --continue' is. Tighten up the check and allow no other
options when one of these sub commands are used.

Only check that it is standalone for non-interactive rebase for
now. Once the command line processing for interactive rebase has been
replaced by the command line processing in git-rebase.sh, this check
will also apply to interactive rebase.

Signed-off-by: Martin von Zweigbergk <martin.von.zweigbergk@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-rebase.sh

@@ -229,6 +229,7 @@ then
 fi
 test -n "$type" && in_progress=t
 
+total_argc=$#
 while test $# != 0
 do
 	case "$1" in
@@ -239,9 +240,8 @@ do
 		OK_TO_SKIP_PRE_REBASE=
 		;;
 	--continue|--skip|--abort)
+		test $total_argc -eq 1 || usage
 		action=${1##--}
-		shift
-		break
 		;;
 	--onto)
 		test 2 -le "$#" || usage