"This all sounds fine to fix without waiting for anything else -- can you attach a patch here?"

I opened the issue as a reminder for me. Here is a patch.

 * Add close() and fileno() methods and a closed attribute (property) to devpoll object
 * Document closed attribute of epoll and kqueue objects
 * Add tests on closed object for devpoll, epoll and kqueue. There was no test for devpoll, epoll nor kqueue :-(

select.poll is still not tested. We should add much more tests, especially tests checking than a fd becomes ready for each implementation. We may develop these tests using #16853 ?

I ran test_select on Linux, so I only checked the epoll unit test.

The "closed" attribute of epoll and kqueue objects should also be documented in Python 2.7 and 3.3.