Crash in `_asyncio._swap_current_task` due to improper reference counting

[chgnrdv]

First appeared in a474e04, where given function was introduced.

Repro:

import _asyncio

class DummyLoop:
    pass

class DummyTask:
    pass

l = DummyLoop()
_asyncio._swap_current_task(l, DummyTask())
t = _asyncio._swap_current_task(l, None)

Output:

Modules/gcmodule.c:461: visit_decref: Assertion "!_PyObject_IsFreed(op)" failed
Enable tracemalloc to get the memory block allocation traceback

object address  : 0x7fedad081130
object refcount : 1
object type     : 0x55f665a81fe0
object type name: dict
object repr     : Segmentation fault (core dumped)

I'm working on a fix.

Linked PRs

• gh-105987: Fix reference counting issue in _asyncio._swap_current_task #105989
• [3.12] gh-105987: Fix reference counting issue in `_asyncio._swap_cur… #106099