Add cookies to the retried request when performing digest authentication.

[musale]

Summary

Adding the cookies from the response in the first request into the follow up request. The server expects a cookie to be set. This is however not highlighted in the RFC. Supporting SO answer and discussions by @robin-blanchard #2788 (comment).

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

[tomchristie]

Nicely done, thanks.

The test suite is failing because there's no coverage for this line...

httpx/httpx/_auth.py

Line 221 in 8302ab2

Cookies(response.cookies).set_cookie_header(request=request)

Do you want to try adding a test case for this?

[musale]

Nicely done, thanks.

The test suite is failing because there's no coverage for this line...

httpx/httpx/_auth.py

Line 221 in 8302ab2

Cookies(response.cookies).set_cookie_header(request=request)

Do you want to try adding a test case for this?

Yes. I'll add a test for it.