Submit handler to update the bundle for the default language configuration.
public function languageConfigurationSubmit(array &$form, array &$form_state) {
$vocabulary = $this->entity;
// Delete the old language settings for the vocabulary, if the machine name
// is changed.
if ($vocabulary && $vocabulary
->id() && $vocabulary
->id() != $form_state['values']['vid']) {
language_clear_default_configuration('taxonomy_term', $vocabulary
->id());
}
// Since the machine name is not known yet, and it can be changed anytime,
// we have to also update the bundle property for the default language
// configuration in order to have the correct bundle value.
$form_state['language']['default_language']['bundle'] = $form_state['values']['vid'];
}