textops(k): free only pkg body lumps for set_body()

- if set_body() is used in failure_route, it should not destroy
  completely the lumps cloned in tm, just ignore them and free the ones
  added in failure_route before execution of itself
- reported by Brandon Armstead, FS#181

modules_k/textops/textops.c

@@ -1259,7 +1259,7 @@ static int set_body_f(struct sip_msg* msg, char* p1, char* p2)
 		return -1;
 	}
 
-	free_lump_list(msg->body_lumps);
+	del_nonshm_lump( &(msg->body_lumps) );
 	msg->body_lumps = NULL;
 
 	if (msg->content_length)