WPT test cookies/http-state/chromium-tests.html times out on a case with "ZYX-Cookie" header

[pshaughn]

Commenting out just the case "disabled-chromium0022" from the list of test cases causes the rest of the file to pass. cookies/http-state/resources/test-files/disabled-chromium0022-test contains ZYX-Cookie: where most tests have Set-Cookie:.

[pshaughn]

Looking at it with RUST_LOG=net output and an extra print statement jammed into the Python code, it looks like:

• we send a simple GET request for http://web-platform.test:8000/cookies/http-state/resources/cookie-setter.py?file=disabled-chromium0022
• the Python code sees this and writes a response successfully into the http connection
• something breaks between there and the next time Servo's net code would write a log statement, leaving the log hanging with an unresponded-to request

[CYBAI]

Did some investigation at #25606 (comment)