SASL stores progress report despite {errlog_type, error}

With this config file:

[
 {gmc开发者_运维百科ontroller, [{config_file, "/mware/config/controller.config"}]},
 %% SASL config
 {sasl, [
         {sasl_error_logger, false},
         {errlog_type, error},
         {error_logger_mf_dir, "log/sasl"},      % Log directory
         {error_logger_mf_maxbytes, 10485760},   % 1 MB max file size
         {error_logger_mf_maxfiles, 5}           % 5 files max
         ]}
].

SASL for some reason keeps progress reports:

4> rb:start([{report_dir, "/mware/log/sasl"}]). 
rb: reading report...done.
rb: reading report...done.
rb: reading report...done.
rb: reading report...done.
rb: reading report...done.

=PROGRESS REPORT==== 13-Apr-2011::16:29:11 ===
          supervisor: {local,sasl_sup}
             started: [{pid,<0.48.0>},
                       {name,rb_server},
                       {mfargs,
                           {rb,start_link,
                               [[{report_dir,
                                     "/mware/log/sasl"}]]}},
                       {restart_type,temporary},
                       {shutdown,brutal_kill},
                       {child_type,worker}]
{ok,<0.48.0>}

5> rb:list().
  No                Type      Process       Date     Time
  ==                ====      =======       ====     ====
 157            progress  <6835.60.0> 2011-04-13 14:10:31
 156            progress  <6835.60.0> 2011-04-13 14:10:31
 ...

I know the config file is being used, because the logfiles are of the correct size and in the expected directory. So what am I doing wrong?

The documentation for errlog_type says:

errlog_type = error | progress | all <optional>

Restricts the error logging performed by the specified sasl_error_logger to error reports, progress reports, or both. Default is all.

I read this to mean that it only applies to what is logged by sasl_error_logger and not by other loggers, the multi-file logger in this case.