mod_http_muc_log: Fix redirect bug If you somehow went to /muc_log/room/yyyy-mm-dd/something it would send you in a redirect loop that continuously added path components until the path can't be parsed anymore. This should ensure that /muc_log/room/date/ is simply 404'd

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.