bridge: Warn about unreadable manifests and overrides
bridge: Warn about unreadable manifests and overrides

This is an user configuration error (most probably wrong permissions)
which should be pointed out a little more strongly.

cockpit-project/cockpit,mvollmer/cockpit,cockpit-project/cockpit,martinpitt/cockpit,cockpit-project/cockpit,mvollmer/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,mvollmer/cockpit,martinpitt/cockpit,martinpitt/cockpit,martinpitt/cockpit,martinpitt/cockpit,mvollmer/cockpit,mvollmer/cockpit