Currently mdapi-get_repo_md re-downloads everything all the time, we should change it to check the sha256 of the file on disk and downloaded and only replace it when the file actually changed.
mdapi-get_repo_md
An other approach, potentially better would be to get that sha256 directly from the the repomd.xml file: http://dl.fedoraproject.org/pub/fedora/linux/development/rawhide/x86_64/os/repodata/repomd.xml
That means, actually loading the xml and parsing it though.
Code to parse the xml can be re-used from : https://github.com/puiterwijk/check_metalink/blob/master/check_metalink#L164
Fixed in 9a398a7.