phptemplate $layout variable never gets set to 'none', breaks some themes when sidebars empty

The phptemplate.engine generates a variable $layout set to one of 4 values depending on whether blocks are enabled iin the standard left and right sidebars and where, the values are 'left', 'right', 'both' or 'none'.

This patch to restrict showing blocks : http://drupal.org/node/80201 seems to have introduced a bug since $layout is now never set to 'none'.

The relevant code is part of the function phptemplate_page in phptemplate.engine:

/**
  * Populate sidebars.
  */
  if ($show_blocks) {
    global $sidebar_indicator;
    /**
     * Sidebar_indicator tells the block counting code to count sidebars separately.
     */
    $sidebar_indicator = 'left';
    $sidebar_left = theme('blocks', 'left');
    if ($sidebar_left != '') {
      $layout = 'left';
    }

    $sidebar_indicator = 'right';
    $sidebar_right = theme('blocks', 'right');
    if ($sidebar_right != '') {
      $layout = ($layout == 'left') ? 'both' : 'right';
    }
    $sidebar_indicator = NULL;
  }
  else {
   $layout = 'none';
  }

For some reason this else never sets $layout to 'none', I don't know why. The patch removes the else and and defines $layout as 'none' by default – suggestions on better ways to fix this appreciated.

If a theme uses $layout to set css class and id for the various possible layouts it can break if no blocks are enabled in the left and right sidebars.

The patch was made against Drupal-5.1 but it's likely this problem persists in 5.x and 6.x dev since this code block hasn't changed.