clarify some error messages wrt unknown object types

If ever new object types are added for future extensions then better
have current git version report them as "unknown" instead of
"corrupted".

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/index-pack.c b/index-pack.c
index 43e007f..5f6d128 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -266,7 +266,7 @@
 	case OBJ_TAG:
 		break;
 	default:
-		bad_object(obj->offset, "bad object type %d", obj->type);
+		bad_object(obj->offset, "unknown object type %d", obj->type);
 	}
 	obj->hdr_size = consumed_bytes - obj->offset;