pythongh-105288: wake up exit waiters after sub-process exits

Lib/asyncio/base_subprocess.py

@@ -217,6 +217,14 @@ def _process_exited(self, returncode):
         self._call(self._protocol.process_exited)
 
         self._try_finish()
+        self._wakeup_exit_waiters()
+
+    def _wakeup_exit_waiters(self):
+        # wake up futures waiting for wait()
+        for waiter in self._exit_waiters:
+            if not waiter.cancelled():
+                waiter.set_result(self._returncode)
+        self._exit_waiters = []
 
     async def _wait(self):
         """Wait until the process exit and return the process return code.
@@ -242,11 +250,7 @@ def _call_connection_lost(self, exc):
         try:
             self._protocol.connection_lost(exc)
         finally:
-            # wake up futures waiting for wait()
-            for waiter in self._exit_waiters:
-                if not waiter.cancelled():
-                    waiter.set_result(self._returncode)
-            self._exit_waiters = None
+            self._wakeup_exit_waiters()
             self._loop = None
             self._proc = None
             self._protocol = None

Misc/NEWS.d/next/Library/2023-06-05-02-48-08.gh-issue-105288.Ewnyas.rst

@@ -0,0 +1,3 @@
+Exit waiters are not resolved after subprocess handled by :class:`asyncio.Task`
+exits. This will causes a recent :func:`asyncio.wait` call hang forever if there
+are objects that are not :type:`Awaitable` yield from its first parameter.