From 67858a90cdb9e5892115115fb9bf6ada64c1451d Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Tue, 8 Jan 2019 02:25:49 +0200
Subject: [PATCH] Fix #3497: Ignore done tasks when cancels pending activities
 on web.run_app finalization.

---
 aiohttp/helpers.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/aiohttp/helpers.py b/aiohttp/helpers.py
index a44a407fea2..cbfbb1e194e 100644
--- a/aiohttp/helpers.py
+++ b/aiohttp/helpers.py
@@ -63,10 +63,15 @@
     from typing_extensions import ContextManager
 
 
-all_tasks = asyncio.Task.all_tasks
+def all_tasks(
+        loop: Optional[asyncio.AbstractEventLoop] = None
+) -> Set['asyncio.Task[Any]']:
+    tasks = list(asyncio.Task.all_tasks(loop))  # type: ignore
+    return {t for t in tasks if not t.done()}
+
 
 if PY_37:
-    all_tasks = getattr(asyncio, 'all_tasks')  # use the trick to cheat mypy
+    all_tasks = getattr(asyncio, 'all_tasks')  # noqa
 
 
 _T = TypeVar('_T')