views_menu_alter adds existing access argument again

Hi,

This week we noticed a new warning on our dev server this week:

Warning: array_fill() [function.array-fill]: Number of elements must be positive in db_placeholders() (line 276 of /var/www/sitename/includes/database.inc).
User warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1 query: SELECT p.perm FROM role r INNER JOIN permission p ON p.rid = r.rid WHERE r.rid IN () in _db_query() (line 169 of /var/www/sitename/includes/database.mysqli.inc).

Digging down I found this is caused in a call to user_access where the account variable was being set to 'administer users'.

function user_access($string, $account = NULL, $reset = FALSE)

This happens because _menu_check_access calls user_access like this:

    if ($callback == 'user_access') {
      $item['access'] = (count($arguments) == 1) ? user_access($arguments[0]) : user_access($arguments[0], $arguments[1]);
    }

arguments[1] in this case should be the user, but instead it's the text string 'administer users' - arguments[0] is also 'administer users'.

The second entry in our case comes from views_menu_alter. The first comes from the user module hook_menu itself.

$callbacks[$path]['access arguments'][] = $item['access arguments'][0];

In the database this creates the following menu_router table entry:

*************************** 1. row ***************************
            path: admin/user/user/create
  load_functions: 
to_arg_functions: 
 access_callback: user_access
access_arguments: a:2:{i:0;s:16:"administer users";i:1;s:16:"administer users";}
   page_callback: user_admin
  page_arguments: a:2:{i:0;s:6:"create";i:1;a:1:{i:0;s:8:"system_1";}}
             fit: 15
    number_parts: 4
      tab_parent: admin/user/user
        tab_root: admin/user/user
           title: Add user
  title_callback: t
 title_arguments: 
            type: 128
  block_callback: 
     description: List, add, and edit users.
        position: 
          weight: 0
            file: modules/user/user.admin.inc

I've attached a patch that checks to see if the access argument already exists before trying to add it. This may not be the best approach but it's fixed the issue for us. Feedback welcome.