It's not standard Python, but must use 'yield' here for correctness

Author: jepler

asyncio/event.py

@@ -62,7 +62,7 @@ async def wait(self):
             self.waiting.push_head(core.cur_task)
             # Set calling task's data to the event's queue so it can be removed if needed
             core.cur_task.data = self.waiting
-            await core.sleep(0)
+            yield
         return True
 
 

asyncio/lock.py

@@ -69,7 +69,7 @@ async def acquire(self):
             # Set calling task's data to the lock's queue so it can be removed if needed
             core.cur_task.data = self.waiting
             try:
-                await core.sleep(0)
+                yield
             except core.CancelledError as er:
                 if self.state == core.cur_task:
                     # Cancelled while pending on resume, schedule next waiting Task