also check for repo existence here, and only add if it's on gitbox
also check for repo existence here, and only add if it's on gitbox

doesn't make sense to add supposed read-only mirrors to the GH team,
so check that the path exists on disk before adding a repo
to a team.

apache/infrastructure-puppet,sebbASF/infrastructure-puppet,apache/infrastructure-puppet,sebbASF/infrastructure-puppet,apache/infrastructure-puppet,sebbASF/infrastructure-puppet,sebbASF/infrastructure-puppet,sebbASF/infrastructure-puppet,apache/infrastructure-puppet,apache/infrastructure-puppet,sebbASF/infrastructure-puppet,sebbASF/infrastructure-puppet,apache/infrastructure-puppet,sebbASF/infrastructure-puppet,apache/infrastructure-puppet