mod_traceback: Hook signal via event instead of directly
Safer this way, see Prosody trunk rev 69faf3552d52
module:hook("authentication-success", function (event)
local session = event.session;
local sasl_handler = session and session.sasl_handler;
local log = session and session.log or module._log
log("info", "Authenticated with %s", sasl_handler and sasl_handler.selected or "legacy auth");
end);