warning: preg_match() expects parameter 2 to be string, array given in [..]/bootstrap.inc on line 737.

I get this warning on two occasions:
* Upon queueing the job
* Upon running cron

After looking at the code, and comparing it with the 5.x-3.0 version, I found a difference that I do not understand. In job_queue_list(), the code creates a table of currently queued jobs. Data rows are created as such:

     $rows[] = array(
        format_date($job->created),
        t($job->description, unserialize($job->arguments)),
      );

whereas in 5.x, they were created as such:

      $rows[] = array(
        format_date($job->created),
        $job->description,
      );

What I don't understand is why are the $arguments used with the $description in 6.x, given that these arguments are intended for the function callback, not for the description. Indeed, when I removed the $arguments from the 6.x snippet above, the code ran without complaining.