git-commit: pass explicit path to git-diff-files.

When running "git commit" with explicit path arguments, allow it to
take directory name.  This makes "git commit Documentation/" to commit
everything that is changed under Documentation/ directory.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/git-commit-script b/git-commit-script
index 790f07c..f6cd75f 100755
--- a/git-commit-script
+++ b/git-commit-script
@@ -88,9 +88,14 @@
 case "$all" in
 t)
 	git-diff-files --name-only -z |
-	xargs -0 git-update-cache -q -- || exit 1 ;;
-esac
-git-update-cache -q --refresh -- "$@" || exit 1
+	xargs -0 git-update-cache -q --
+	;;
+*)
+	git-diff-files --name-only -z "$@" |
+	xargs -0 git-update-cache -q --
+	;;
+esac || exit 1
+git-update-cache -q --refresh || exit 1
 
 case "$verify" in
 t)