Administrators get messed up menus

A user who has the 'administer nodes' permission but not the 'access content' permission will not see any node links in menus.

This regression was introduced as part of a fix for SA-CORE-2015-003. The offending code is:

function menu_tree_check_access(&$tree, $node_links = array()) {

  if ($node_links && (user_access('access content') || user_access('bypass node access'))) {

The fix introduced those two calls to user_access, however the 'bypass node access' permission does not exist in Drupal 6.

This can be worked around by granting 'access content' to any role that has 'administer nodes'.