gh-128588: gh-128550: remove eager tasks optimization that missed and introduced incorrect cancellations (#129063)

Co-authored-by: Kumar Aditya <kumaraditya@python.org>

1 files changed, 5 insertions, 7 deletions

diff --git a/Lib/asyncio/taskgroups.py b/Lib/asyncio/taskgroups.py
index 8af199d6dcc..8fda6c8d55e 100644
--- a/Lib/asyncio/taskgroups.py
+++ b/Lib/asyncio/taskgroups.py
@@ -197,14 +197,12 @@ class TaskGroup:
         else:
             task = self._loop.create_task(coro, name=name, context=context)
 
-        # optimization: Immediately call the done callback if the task is
+        # Always schedule the done callback even if the task is
         # already done (e.g. if the coro was able to complete eagerly),
-        # and skip scheduling a done callback
-        if task.done():
-            self._on_task_done(task)
-        else:
-            self._tasks.add(task)
-            task.add_done_callback(self._on_task_done)
+        # otherwise if the task completes with an exception then it will cancel
+        # the current task too early. gh-128550, gh-128588
+        self._tasks.add(task)
+        task.add_done_callback(self._on_task_done)
         try:
             return task
         finally: