Langcode not passed to hook_commerce_currency_info_alter

According to commerce.api.php hook_commerce_currency_info_alter is supposed to be passed a langcode:

function hook_commerce_currency_info_alter(&$currencies, $langcode) {
  $currencies['CHF']['code_placement'] = 'after';
}

But commerce_currencies() fails to do so:

drupal_alter('commerce_currency_info', $currencies['all']);