Nagios reports ok for approx 1 hour daily, when core updates are required

So the problem centres around this bit of code in nagios.module on 6.x:

nagios.module - lines 398 - 417

  $severity = REQUIREMENT_OK;
  $min_severity = variable_get('nagios_min_report_severity', NAGIOS_STATUS_WARNING);
  foreach ($reqs as $key => $requirement) {
    if (isset($requirement['severity'])) {
      // Ignore update_core warning if update cache has expired and nagios_cron_duration has not passed by yet
      if ($key == 'update_core' && $requirement['severity'] == REQUIREMENT_WARNING && $requirement['reason'] == UPDATE_UNKNOWN) {
        $grace = 60 * variable_get('nagios_cron_duration', 60);
        $expire = db_result(db_query("SELECT expire FROM {cache_update} WHERE cid = '%s'", 'update_available_releases'));
        if ($expire && time() < ($expire + $grace)) {
          continue;
        }
      }
      if ($requirement['severity'] >= $min_severity) {
        if ($requirement['severity'] > $severity) {
          $severity = $requirement['severity'];
        }
        $descriptions[] = $requirement['title'];
      }
    }
  }

So on 398, the severity is set to OK - a sensible default. The module then checks the requirements for updates, and loops over them.

The issue is that if the site is only looking for core updates (or only requires core updates), for the duration that time() is less than $expire + $grace (which defaults to 60 minutes), the severity is not reset due to the continue; on the loop, resulting in a false OK status being returned.