As per the discussion in
MDL-22895 and dev chat. Any "loss of functionality" is a stable bug and thus needs to be ported to all stable branches
We should be able to backup course events when course backup is performed. And do that controlled by one setting in backup (defaulting to yes).
See backup_events_info() under Moodle 1.9.
Then, restore will allow to restore that information if available and also, optionally controlled by one setting.