use the same redirection handling for http and https

use the same redirection handling for http and https

cURL which backs our https implementation can handle redirects on its
own, but by dealing with them on our own we gain finer control over which
redirections will be performed (we don't like https → http) and by whom
so that redirections to other hosts correctly spawn a new https method
dealing with these instead of letting the current one deal with it.