How to handle "curl -XGET http://testdomain.com --request-target example.com:80" with Gorilla

How do I create a Path or PathPrefix in Gorilla http framework if the user forces a URI that does not begin with a slash? This causes a direct to whatever the user specifies, e.g.:

# curl -Iv http://testdomain.com --request-target example.com:80
* Added testdomain.com to DNS cache
* Hostname testdomain.com was found in DNS cache
> HEAD example:80 HTTP/1.1
> Host: testdomain.com
> User-Agent: curl/7.79.1
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 301 Moved Permanently
HTTP/1.1 301 Moved Permanently
< Location: example:80
Location: example:80
< Date: Fri, 28 Oct 2022 18:53:03 GMT
Date: Fri, 28 Oct 2022 18:53:03 GMT
<
* Connection #0 to host REDACTED left intact

Currently, it does not match anything in my route setup, yet generates a redirect. Middle-ware is also not catching anything to act on:

func filterMW(next http.Handler) http.Handler {
    logrus.Infof("In filterMW")
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    dump, _ := httputil.DumpRequest(r, false)
    logrus.Infof("%v", string(dump))
    next.ServeHTTP(w, r)
    })
}

httpRouter := mux.NewRouter()
httpRouter.Use(filterMW)

Thoughts?

Edit: Updated to include more details!