How can I reproduce this issue locally?

@karpetrosyan use async interface and socks5 proxy.

e.g.:

#! /usr/bin/env python

import asyncio
import httpx


async def trace_func(event, data):
    print(f'{event=} {data=}')

async def make_request():
    async_client = httpx.AsyncClient(
        proxies={'all://': 'socks5://non-existed-domain.com'},
    )

    async with async_client as client:
        response = await client.request(
            "GET", "https://www.encode.io", extensions={"trace": trace_func}
        )
        print(response)

asyncio.run(make_request())

Yes, I see the problem.
We appear to have accidentally used the synchronous context manager in the asynchronous code.
Thank you 🙏

We also need a changelog for this PR.

@karpetrosyan added

I wonder why person who added this code haven't covered this with tests.
So will leave it for you guys.
We workarounded this in production anyway, as your release process is not fast.

I wonder why person who added this code haven't covered this with tests.

The code is actually covered, at least, because we have 100% code coverage.

So will leave it for you guys.

If you have found a bug that has not been tested and you have considered opening the pull request to fix that bug, you MUST add a test case, especially when it was requested by the maintainer.

There are rules for how this project should be maintained.
You cannot do just a part of the pull request and let the rest of the work be done by others.
If you had considered opening the pull request, you should either do it fully or don't do it at all.

Anyway, I think we don't need a test case for this pull request. Maybe we could add a rule to unasync.py so we can avoid this kind of situation.

If @zanieb is okay with that, we can skip the test case for this change.

Thanks for this pull request @cono 🙏

Guys, you have a bug in a library which crash application in particular circumstances, and isntead of accepting 2 line changes, you making discussion for 2 days about nothing. It's kinda like a joke to me.
Do whatever you want. "MUST" is too strong for me, I don't owe you anything. Good luck