re-enable multiple test runs in sequence for 4.1 on non-windows

    {

      # Only platforms that have native symlinks can use the vardir trick

      $opt_mem= $opt_vardir;

      # Delete the default directory in case it exists since we're going to create

      # a new one later anyway, and the mkpath below throws a fatal error otherwise

      eval { rmtree($default_vardir, 1, 1); };

      mtr_report("Using 4.1 vardir trick");

    }