Use MainContext::with_thread_default() instead of pushing/popping man…

src/main_context_futures.rs

@@ -214,9 +214,7 @@ impl TaskSource {
 
             // Clone that we store in the task local data so that
             // it can be retrieved as needed
-            executor.push_thread_default();
-
-            let res = {
+            let res = executor.with_thread_default(|| {
                 let enter = futures::executor::enter().unwrap();
                 let mut context = Context::from_waker(&waker);
 
@@ -225,9 +223,8 @@ impl TaskSource {
                 drop(enter);
 
                 res
-            };
+            });
 
-            executor.pop_thread_default();
             res
         } else {
             Poll::Ready(())