Fedora 27 Generic release interference with Virtualbox

Recently I upgraded to Fedora 27. Everything was smooth except that Oracle Virtualbox stopped working after some time.
I first thought that this is a problem with Virtualbox and thought of even upgrading to new version and do everything from scratch.
But it wasn't and I was lucky not doing it. I realised that it was Fedora generic-release to be blamed. A simple search has led me to this reddit page and it was easy to switch back to fedora-release. Virtualbox started working as it did before.

Dnf fastestmirror

I was trying to upgrade Fedora 24 to 25. The mirror dnf using was poor. I interrupted the download process many times with the hope that it will connect at a much more speed. But at last I decided to change the mirror that dnf uses.
While searching for the correct code to do this, I noticed that there is a plugin that forces dnf use the fastest mirror (fastestmirror). It was already installed in my box but dnf was not instructed to use it. Hence a simple line

fastestmirror=true

in dnf.conf solved my issue.