lib/private/User,apps/user_ldap/lib/User: always pass old value to User::triggerChange

lib/private/User/User.php

@@ -138,11 +138,12 @@ class User implements IUser {
 	 */
 	public function setDisplayName($displayName) {
 		$displayName = trim($displayName);
+		$oldDisplayName = $this->getDisplayName();
 		if ($this->backend->implementsActions(Backend::SET_DISPLAYNAME) && !empty($displayName)) {
 			$result = $this->backend->setDisplayName($this->uid, $displayName);
 			if ($result) {
 				$this->displayName = $displayName;
-				$this->triggerChange('displayName', $displayName);
+				$this->triggerChange('displayName', $displayName, $oldDisplayName);
 			}
 			return $result !== false;
 		}