mod_pubsub_serverinfo: Treat public providers as public The opt-in mechanism is to prevent leaking domain names or relationships between small private servers. These are not considerations relevant to public servers. We use the providers.xmpp.net API to fetch a list of known public provider domains.

This module writes out a traceback to `traceback.txt` in Prosodys data
directory (see `prosodyctl about`) when the signal `SIGUSR1` is
received. This is useful when debugging seemingly frozen instances in
case it is stuck in Lua code.