A GET request to https://www.mediawiki.org/wiki/Special:RunJobs returns the correct HTTP status code 400 Bad Request, but with not correct specified content: It has the HTTP header Content-Type: text/html and the plain text content Request must be POSTed.

$ curl -i --http1.1 https://www.mediawiki.org/wiki/Special:RunJobs
HTTP/1.1 400 Bad Request
[...]
Content-Type: text/html
[...]

Request must be POSTed

https://validator.w3.org/check?uri=https%3A%2F%2Fwww.mediawiki.org%2Fwiki%2FSpecial%3ARunJobs&No200=1

Expected result: Either the Content-Type is text/plain or the content text is a HTML document.