Fix for sprintfn function for named arguments (http://php.net/manual/en/function.sprintf.php#94608):

Change the first line from:
  $arg_nums = array_slice(array_flip(array_keys(array(0 => 0) + $args)), 1);
to:
  $arg_nums = array_keys($args);
  array_unshift($arg_nums, 0);
  $arg_nums = array_flip(array_slice($arg_nums, 1, NULL, true));