URIs cannot have custom ports

[Steve Kemp]

The following fails:

   http://localhost:8080/ must run http

There is a DNS-failure trying to resolve the hostname localhost:8080. Even if that worked though we have a second issue - we look at the URI to find the port:

port := 80
if strings.HasPrefix(tst.Target, "https:") {
	port = 443
}

So that needs updating too.