Intermittent FAIL in /xhr/send-redirect.htm

[Loirooriol]

https://github.com/servo/servo/actions/runs/8616190827/job/23614665394

  ▶ OK /xhr/send-redirect.htm
  │   ▶ FAIL [expected PASS] XMLHttpRequest: send() - Redirects (basics) (303 does redirect)
  │   │   → assert_equals: expected (string) "GET" but got (object) null
  │   │ 
  │   │ redirect/</client.onreadystatechange/<@http://web-platform.test:8000/xhr/send-redirect.htm:22:32
  │   │ Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:2622:25
  └   └ redirect/</client.onreadystatechange@http://web-platform.test:8000/xhr/send-redirect.htm:19:18