Make dnf/yum work when hung

If you get a error while using you or dnf and it seems like it cant connect to the downloadserver or that the process is interupted.

The fix is, thankfully, rather easy: remove the RPM database, rebuild it and let dnf/yum download all the mirror's file lists.

$ mv /var/lib/rpm/__db* /tmp/
$ rpm --rebuilddb
$ yum clean all