This bug is related to a mitigation for the ALPACA security issue. The relevant Pull Request for the fetch repo is at https://github.com/whatwg/fetch/pull/1250 and WPT have already been adjusted.
<rdar://problem/79287147>
Created attachment 431928 [details] Patch
This patch modifies the imported WPT tests. Please ensure that any changes on the tests (not coming from a WPT import) are exported to WPT. Please see https://trac.webkit.org/wiki/WPTExportProcess
Comment on attachment 431928 [details] Patch r=me
Created attachment 431933 [details] Patch
Committed r279099 (239016@main): <https://commits.webkit.org/239016@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 431933 [details].