Code review comment for lp:~afrantzis/mir/fix-1514391-mircookie-nettle-dev-dependency

> Shouldn't everything we need from nettle be provided transitively by libmircookie?

That's a good point. It doesn't seem that Requires.private is needed at all anymore. It is probably a leftover from when cookie_factory.h included <nettle/hmac.h> (which was only for a short while and I am not sure if that version ever hit trunk anyway).