Preserve built-in event handler order

Author: gabotechs

src/events/common.rs

@@ -50,7 +50,7 @@ impl<H: ?Sized + Send + Sync + 'static> EventHandlerChain<H> {
             .get_extension::<Self>()
             .map(|v| v.as_ref().clone())
             .unwrap_or_default();
-        for handler in handler_list.into_iter().rev() {
+        for handler in handler_list {
             handlers.builtin.push(handler);
         }
         cfg.set_extension(Arc::new(handlers));

src/events/defaults/routing.rs

@@ -49,6 +49,9 @@ pub(crate) fn single_task_coordinator_routing(
 pub(crate) fn single_task_child_url_routing(
     ev: RouteTasksEvent,
 ) -> Option<Result<RouteTasksEventResponse>> {
+    if ev.task_count != 1 {
+        return None;
+    }
     let mut single_stage_url = None;
     ev.plan
         .apply(|plan| {