Migration Plugin

at the time pulp2 content will start the migration, pulp2 repos will be migrated already. Content that depends on the repository, at the migration time should check whether pulp2 repo was already migrated, if the corresponding repo is not migrated, do not migrate this content and skip

Thinking more about it, I realised that there is a reason I wrote skipped at migration time. It will be pre-migrated but not moved further in the description. Remember that we rely on the timestamp of migration to pre-migrate the content. If we skip the content at the pre-migration time, it will never be migrated. So I suggest to skip at migration time as it is written now.