Unable to propagate error messages from auxprop_lookup to sasl_server_step() caller

Greetings,

We have an auxprop plugin that we are using in conjunction with the
digest-md5 plugin. It looks like I'm running into an issue where the error
message that I set within the auxprop_lookup() function  (via
utils->seterror() ) is being overwritten by this line, as it returns up the
call stack:
https://github.com/cyrusimap/cyrus-sasl/blob/master/plugins/digestmd5.c#L2567

Should there be a way for the plugin to set the error message that will be
returned by the sasl_server_step() function?

Best,
-Joe