Bug report

Bug description:

Hello,

the following snippet raises an exception in Python 3.13.2 while it's fine with Python 3.12.

import io
import gzip

def foo():
    buffer = gzip.GzipFile(fileobj=io.BytesIO(), mode="w")

foo()

Running this with python3.12 is silent, with Python 3.13.2 instead:

Exception ignored in: <gzip on 0x7fa4fd99c550>
Traceback (most recent call last):
  File "/usr/lib/python3.13/gzip.py", line 359, in close
    fileobj.write(self.compress.flush())

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Linked PRs

• gh-129726: Break gzip.GzipFile reference loop #130055
• [3.13] gh-129726: Break gzip.GzipFile reference loop (GH-130055) #130669
• [3.12] gh-129726: Break gzip.GzipFile reference loop (GH-130055) #130670