Wrong fallbacks for mirrorbits

the fallback mirrors I see in mirrorbits don't seem right:

1. sv.mirrors.kernel.org this hostname doesn't exist
2. mirror1001.wikimedia.org this sort of works, except ssl is broken, because its certificate is only valid for https://mirrors.wikimedia.org/ .

In both cases, I think we're trying to look for the exact machine where the mirror might be held, but that's not how these mirrors system work (anymore?) maybe.

This has practical implications. When mirrorbits doesn't know about a file copy being available on any mirror, it will redirect the user to one of those fallback mirrors. Since they don't work, no download can happen. This means the whole point of fallback mirrors is defeated!

Please note that fixing only one of them wouldn't be enough, because the user is redirected deterministically, always to the same mirror, based on their geographic position.