How Can I Make the Go HTTP Client NOT Follow Redirects Automatically?

There’s a much simpler solution right now:

client := &http.Client{
    CheckRedirect: func(req *http.Request, via []*http.Request) error {
        return http.ErrUseLastResponse
    },
}

This way, the http package automatically knows: “Ah, I shouldn’t follow any redirects”, but does not throw any error. From the comment in the source code:

As a special case, if CheckRedirect returns ErrUseLastResponse,
then the most recent response is returned with its body
unclosed, along with a nil error.