Add reference to GH issue

Author: duaneg

Lib/test/test_concurrent_futures/test_thread_pool.py

@@ -113,6 +113,7 @@ def log_n_wait(ident):
         self.assertListEqual(log, ["ident='first' started", "ident='first' stopped"])
 
     def test_shutdown_cancels_pending_futures(self):
+        # gh-109934: ensure shutdown cancels and notifies pending futures
         def waiter(barrier):
             barrier.wait(3)
         def noop():