Give all permissions back to the admin role

my_custom_module.install.php

<?php
/**
 * Give admin role permissions to all modules on site.
 */
function my_custom_module_update_7001() {
  $permissions = array();

  foreach (module_implements('permission') as $module) {
    $module_permissions = module_invoke($module, 'permission');

    foreach (array_keys($module_permissions) as $permission) {
      $permissions[$permission] = TRUE;
    }
  }

  $admin_role = variable_get('user_admin_role');
  user_role_change_permissions($admin_role, $permissions);
}

Should be my_custom_module.install but gist highlighting breaks.