There is the case where OCs IDs might become outdated such as it has been with the calendar and contacts app which refer to the old dummy entry. This means that users with the old OCS id can't update updates as well will receive invalid state flags. (e.g. "experimental" instead of "approved")
To allow instances to properly update the applications in the future we need to migrate the OCS IDs for now manually.
Morris Jobke
Lukas Reschke