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>

builtin-bundle.c

@@ -328,11 +328,9 @@ static int create_bundle(struct bundle_header *header, const char *path,
 		 * other limiting options could have prevented all the tips
 		 * from getting output.
 		 */
-		if (!(e->item->flags & SHOWN)) {
-			warn("ref '%s' is excluded by the rev-list options",
+		if (!(e->item->flags & SHOWN))
+			die("ref '%s' is excluded by the rev-list options",
 				e->name);
-			continue;
-		}
 		write_or_die(bundle_fd, sha1_to_hex(e->item->sha1), 40);
 		write_or_die(bundle_fd, " ", 1);
 		write_or_die(bundle_fd, ref, strlen(ref));