async_event: set doesn't awake waiters

[anarthal]

capy::task<void> set_event(capy::async_event& evt)
{
   evt.set();
   co_return;
}

capy::task<void> co_main()
{
   capy::async_event evt;
   co_await capy::when_all(evt.wait(), set_event(evt));
   std::cout << "Finished\n";
}

int main()
{
   corosio::io_context ctx;
   capy::run_async(ctx.get_executor())(co_main());
   ctx.run();
}

Expected: the program finishes immediately
Actual: the program hangs forever