#1126 mod_cloud_notify/mod_smacks: persist 0198 zombie while push is enabled
The combination of SM and push allows us to keep a client session for a much longer time, without the short SM timeout typically configured for uncertain situations (we don't know if the client will come back, so we terminate the SM zombie after ~5mins).
If we stop the zombie termination countdown (read: smacks hibernation timeout) on sessions that have push notifications enabled, we can assume that the client will come back and resume as soon as we push a message to it. If the client wasn't killed, it will be able to resume the session. If it was killed it will come with a new session and the old one gets destroyed. If the client was dropped into the pool, we'll get an error from the respective push service and can kill the zombie.
In ejabberd, the following logic is applied:
* on 0198 hibernation, only set the timeout if no push is active
* when a push message is sent, start the normal hibernation timeout
* if the push is responded to with an error, kill the zombie (IIRC)