There have been two protocol related issues with MirrorManager open for some time:
Both issues have been resolved. The first issue, to drop FTP URLs from the metalinks, has been resolved in multiple steps. The first step was to block FTP URLs from being added to Fedora's MirrorManager (Optionally exclude certain protocols from MM, New MirrorManager2 features) and the second step, to remove all remaining FTP URLs from Fedora's MirrorManager, was performed during the last few days and weeks. Using MirrorManager's mirrorlist interface (which is not used very often) only returned FTP if the mirror had no HTTP(S) URLs. So it was already rather unusual to be redirected to a FTP mirror. Using MirrorManager's metalink interface returned all possible URLs for a host. With the removal of all FTP URLs from MirrorManager's database no user should see FTP URLs any more and the problems some clients encoutered (see Drop ftp:// urls from metalinks) should be 'resolved'.
The other issue (Add a way to specify you want only https urls from metalink) has also been solved by adding a protocol option to the mirrorlist and metalink back-end. The new MirrorManager release (0.7.2) which includes these changes is already running on the staging instance and the result can be seen here:
To have more HTTPS based mirrors in our database we scanned all existing public mirrors to see if they also provide HTTPS. With this the number of HTTPS URLs was increased from 24 to over 120.
The option to select which protocol the mirrorlist/metalink mirrors should provide is not yet running on the production instance.