fix cases of exception in task group body before/after cancel()

Author: belm0

Lib/asyncio/taskgroups.py

@@ -150,10 +150,6 @@ async def _aexit(self, et, exc):
                 # If there are no pending cancellations left,
                 # don't propagate CancelledError.
                 propagate_cancellation_error = None
-                # If Cancelled would actually be raised out of the TaskGroup,
-                # suppress it-- this is significant when using stop().
-                if not self._errors:
-                    return True
 
         # Propagate CancelledError if there is one, except if there
         # are other errors -- those have priority.
@@ -184,6 +180,10 @@ async def _aexit(self, et, exc):
             finally:
                 exc = None
 
+        # If we wanted to raise an error, it would have been done explicitly
+        # above.  Otherwise, either there is no error or we want to suppress
+        # the original error.
+        return True
 
     def create_task(self, coro, *, name=None, context=None):
         """Create a new task in this group and return it.

Lib/test/test_asyncio/test_taskgroups.py

@@ -1063,6 +1063,20 @@ async def raise_exc(parent_tg: asyncio.TaskGroup):
                 tg.create_task(raise_exc(tg))
                 await asyncio.sleep(1)
 
+    async def test_taskgroup_body_cancel_before_exception(self):
+        with self.assertRaises(ExceptionGroup):
+            async with asyncio.TaskGroup() as tg:
+                tg.cancel()
+                raise RuntimeError
+
+    async def test_taskgroup_body_cancel_after_exception(self):
+        with self.assertRaises(ExceptionGroup):
+            async with asyncio.TaskGroup() as tg:
+                try:
+                    raise RuntimeError
+                finally:
+                    tg.cancel()
+
 
 if __name__ == "__main__":
     unittest.main()