test suite hangs after upgrading websockets from 13.1 to 15.0.1

[apteryks]

Hi,

After upgrading the python-websockets from 13.1 to 15.0.1 in Guix, python-httpx hangs on its test suite:

starting phase `check'
Using pytest
============================= test session starts ==============================
platform linux -- Python 3.11.14, pytest-8.4.1, pluggy-1.6.0 -- /gnu/store/76vhpdf5vc4rvr1rbcd0p0ycj0npjypb-python-wrapper-3.11.14/bin/python
cachedir: .pytest_cache
hypothesis profile 'default'
rootdir: /tmp/guix-build-python-httpx-0.28.1.drv-0/source
configfile: pyproject.toml
plugins: hypothesis-6.135.26, asyncio-1.0.0, trio-0.8.0, anyio-4.6.2
asyncio: mode=Mode.AUTO, asyncio_default_fixture_loop_scope=None, asyncio_default_test_loop_scope=function
collecting ... collected 1407 items / 5 deselected / 1402 selected
[ hung up ]

[apteryks]

That's with Python 3.11.14 and the following inputs:

nss-certs-for-test@3.101.4 python-anyio@4.6.2 python-brotli@1.0.9 python-certifi@2025.06.15
+ python-chardet@5.2.0 python-cryptography@44.0.3 python-h2@4.1.0 python-hatch-fancy-pypi-readme@25.1.0
+ python-hatchling@1.27.0 python-httpcore@1.0.9 python-idna@3.10 python-pytest-asyncio@1.0.0 python-pytest-trio@0.8.0
+ python-pytest@8.4.1 python-setuptools@80.9.0 python-sniffio@1.3.1 python-socksio@1.0.0 python-trio@0.28.0
+ python-trustme@1.2.1 python-uvicorn@0.38.0 python-zstandard@0.23.0

[mirthebeijers]

see #3693 --> it would be great to have @lovelydinosaur feedback on that PR

[apteryks]

@mirthebeijers I tried it on top of httpx commit ae1b9f6, but it doesn't resolve the issue (the test suite still hangs).

[akx]

FWIW, the test suite will hang inexplicably if port 8000 is reserved. #3775 fixes that.