git-reset: complain and exit upon seeing an unknown parameter.

The check to use "rev-parse --verify" was defeated by the use of
"--default HEAD".  "git reset --hard bogus-committish" just
defaulted to reset to the HEAD without complaining.

Signed-off-by: Junio C Hamano <junkio@cox.net>

git-reset.sh

@@ -17,7 +17,11 @@ case "$1" in
         usage ;;
 esac
 
-rev=$(git-rev-parse --verify --default HEAD "$@") || exit
+case $# in
+0) rev=HEAD ;;
+1) rev=$(git-rev-parse --verify "$1") || exit ;;
+*) usage ;;
+esac
 rev=$(git-rev-parse --verify $rev^0) || exit
 
 # We need to remember the set of paths that _could_ be left