Configuration page fails to render with error

After enabling live_person from the 7.x-1.x branch, and getting admin/config/system/live-person, I don't see the configuration form, and I get this error:

Warning: Parameter 1 to live_person_admin_settings_form() expected to be a reference, value given in drupal_retrieve_form() (line 772 of /var/www/drupal_7/includes/form.inc).

I think the problem is the &$form_state parameter in the signature of live_person_admin_settings_form(&$form_state).

The D7 module tutorial suggests that the signature should be ($form, &$form_state) instead, and ths suggests that the signature should be ($form, &$form_state)