# File monit/lib/symbiosis/monitor/state_db.rb, line 84
      def failed_since(test)
        s = last_success(test)
        t = s.nil? ? 0 : s['timestamp']
        r = @dbh.execute("SELECT timestamp FROM #{@tbl_name} WHERE test = ? AND timestamp > ? AND exitstatus != 0 ORDER BY timestamp DESC limit 0,1", test, s['timestamp']).first
        r.nil? ? nil : r['timestamp']
      end