Treat HEAD the same as GET #4512
Description
c.f. #4483 (comment)
There's plenty of cases where we send 4xx responses to HEAD requests, but not to an identical GET request.
c.f. https://httpwg.org/specs/rfc9110.html#HEAD:
The HEAD method is identical to GET except that the server MUST NOT send content in the response. HEAD is used to obtain metadata about the selected representation without transferring its representation data, often for the sake of testing hypertext links or finding recent modifications.
The server SHOULD send the same header fields in response to a HEAD request as it would have sent if the request method had been GET. However, a server MAY omit header fields for which a value is determined only while generating the content.