Fix: Regression detected by PHPUnit

htdocs/adherents/class/adherent.class.php

htdocs/comm/action/class/actioncomm.class.php

htdocs/core/class/commonobject.class.php

htdocs/product/class/product.class.php

htdocs/societe/class/societe.class.php

htdocs/user/class/user.class.php