Queue non-immediate shutdown doesn't unblock getters

[EpicWink]

Bug report

Bug description:

Caused by #104750

import queue
import threading

q = queue.Queue()
t = threading.Thread(target=q.get)
t.start()
q.shutdown()
t.join(timeout=10.0)
assert not t.is_alive() # raises AssertionError

Discovered here: #104228 (comment)

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-117531: Unblock getters after non-immediate queue shutdown #117532