
The repo format has slightly changed for CentOS 8 (s/os/baseos/). Make the chroot builder look for a more specific repos.d directory first named for the distro variable, then fall back to to top-level dir (this avoids having to constantly change fedora). Update the gate mirror setup and roles for new Centos 8 paths too. Change-Id: I5b7f0c3624cac1d7aa7ed8bf6286b85d808b9c9a