mod_pubsub_subscription: Match stanzas with fixed prefix only This should help filter out any other unrelated iq stanzas which may be exchanged with the pubsub service. For example, a separate module was requesting the item list from a subscribed node, but this module was incorrectly attempting to handle the result.

---
summary: Log a message once per minute
...

This module sends `-- MARK --` to the log once per minute. This may be
useful to give a sense of how busy the server is or see that logging and
timers are still working.