Comment 1 for bug 2025978

At this revision, we lost an ability of installing from a mirrored repository:
https://git.launchpad.net/landscape-charm/commit/config.yaml?h=main&id=01f72f99b84fcf8e7c8eef81883abb12209e3461

Installation from a mirror server can happen where a child Landscape doesn't have internet access but to fetch packages from a parent Landscape in DMZ in some enterprise requirements.