diff --git a/apps/testing/appinfo/app.php b/apps/testing/appinfo/app.php
new file mode 100644
index 0000000000..402889f267
--- /dev/null
+++ b/apps/testing/appinfo/app.php
@@ -0,0 +1,23 @@
+<?php
+/**
+ * @author Vincent Petry <pvince81@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud GmbH.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+$app = new \OCA\Testing\Application();
+
diff --git a/apps/testing/appinfo/info.xml b/apps/testing/appinfo/info.xml
index 35ee3715b5..bd64fca212 100644
--- a/apps/testing/appinfo/info.xml
+++ b/apps/testing/appinfo/info.xml
@@ -9,4 +9,7 @@
 	<dependencies>
 		<nextcloud min-version="12" max-version="12" />
 	</dependencies>
+	<types>
+		<type>prelogin</type>
+	</types>
 </info>
diff --git a/apps/testing/lib/AlternativeHomeUserBackend.php b/apps/testing/lib/AlternativeHomeUserBackend.php
new file mode 100644
index 0000000000..1e86b0bc55
--- /dev/null
+++ b/apps/testing/lib/AlternativeHomeUserBackend.php
@@ -0,0 +1,56 @@
+<?php
+/**
+ * @author Vincent Petry <pvince81@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud GmbH.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\Testing;
+
+/**
+ * Alternative home user backend.
+ *
+ * It returns a md5 of the home folder instead of the user id.
+ * To configure, need to add this in config.php:
+ *	'user_backends' => [
+ *			'default' => false, [
+ *				'class' => '\\OCA\\Testing\\AlternativeHomeUserBackend',
+ *				'arguments' => [],
+ *			],
+ *	]
+ */
+class AlternativeHomeUserBackend extends \OC\User\Database {
+	public function __construct() {
+		parent::__construct();
+	}
+	/**
+	 * get the user's home directory
+	 * @param string $uid the username
+	 * @return string|false
+	 */
+	public function getHome($uid) {
+		if ($this->userExists($uid)) {
+			// workaround to avoid killing the admin
+			if ($uid !== 'admin') {
+				$uid = md5($uid);
+			}
+			return \OC::$server->getConfig()->getSystemValue('datadirectory', \OC::$SERVERROOT . '/data') . '/' . $uid;
+		}
+
+		return false;
+	}
+}
diff --git a/apps/testing/lib/Application.php b/apps/testing/lib/Application.php
new file mode 100644
index 0000000000..19eda60acb
--- /dev/null
+++ b/apps/testing/lib/Application.php
@@ -0,0 +1,30 @@
+<?php
+/**
+ * @author Vincent Petry <pvince81@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud GmbH
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\Testing;
+
+use OCP\AppFramework\App;
+
+class Application extends App {
+	public function __construct (array $urlParams = array()) {
+		parent::__construct('testing', $urlParams);
+	}
+}
diff --git a/lib/private/legacy/user.php b/lib/private/legacy/user.php
index ed0d14a1ab..0a52be7565 100644
--- a/lib/private/legacy/user.php
+++ b/lib/private/legacy/user.php
@@ -125,9 +125,16 @@ class OC_User {
 	 * setup the configured backends in config.php
 	 */
 	public static function setupBackends() {
-		OC_App::loadApps(array('prelogin'));
-		$backends = \OC::$server->getSystemConfig()->getValue('user_backends', array());
+		OC_App::loadApps(['prelogin']);
+		$backends = \OC::$server->getSystemConfig()->getValue('user_backends', []);
+		if (isset($backends['default']) && !$backends['default']) {
+			// clear default backends
+			self::clearBackends();
+		}
 		foreach ($backends as $i => $config) {
+			if (!is_array($config)) {
+				continue;
+			}
 			$class = $config['class'];
 			$arguments = $config['arguments'];
 			if (class_exists($class)) {