bpo-46771: Remove two controversial lines from Task.cancel() (GH-31623)

Also from the _asyncio C accelerator module,
and adjust one test that the change caused to fail.

For more discussion see the discussion starting here:
https://github.com/python/cpython/pull/31394#issuecomment-1053545331

(Basically, @asvetlov proposed to return False from cancel()
when there is already a pending cancellation, and I went along,
even though it wasn't necessary for the task group implementation,
and @agronholm has come up with a counterexample that fails
because of this change.  So now I'm changing it back to the old
semantics (but still bumping the counter) until we can have a
proper discussion about this.)

1 files changed, 7 insertions, 3 deletions

diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index 8847123..2a6c0b3 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -2206,9 +2206,13 @@ _asyncio_Task_cancel_impl(TaskObj *self, PyObject *msg)
     }
 
     self->task_num_cancels_requested += 1;
-    if (self->task_num_cancels_requested > 1) {
-        Py_RETURN_FALSE;
-    }
+
+    // These three lines are controversial.  See discussion starting at
+    // https://github.com/python/cpython/pull/31394#issuecomment-1053545331
+    // and corresponding code in tasks.py.
+    // if (self->task_num_cancels_requested > 1) {
+    //     Py_RETURN_FALSE;
+    // }
 
     if (self->task_fut_waiter) {
         PyObject *res;