mod_http_oauth2: Make note about handling repeated RFC 6749 states > If an authorization code is used more than once, the authorization > server MUST deny the request and SHOULD revoke (when possible) all > tokens previously issued based on that authorization code. We should follow the SHOULD. The MUST is already covered by removing the code state from the cache.

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.