ZP-952 Fixed variable name.

Released under the Affero GNU General Public License (AGPL) version 3.

src/lib/core/synccollections.php

@@ -598,7 +598,7 @@ class SyncCollections implements Iterator {
                     $folderid = ZPush::GetDeviceManager()->GetFolderIdForBackendId($backendFolderId);
 
                     // Check hierarchy notifications
-                    if ($folderid === IBackend::HIERARCHYNOTIFICATION) {
+                    if ($backendFolderId === IBackend::HIERARCHYNOTIFICATION) {
                         // wait two seconds before validating this notification, because it could potentially be made by the mobile and we need some time to update the states.
                         sleep(2);
                         // check received hierarchy notifications by exporting