Added support for extra backends (see pull request #5043)

Somebody had forgotten "OC_User::setupBackends();"...

diff --cc lib/private/connector/sabre/auth.php
index 0c84fa6b7578e85656fb042ece59a13642f44276,0000000000000000000000000000000000000000..43beb5e3f66300afa053548bba8e1ca74d2fee79
mode 100644,000000..100644
--- 1/lib/private/connector/sabre/auth.php
--- /dev/null
+++ b/lib/private/connector/sabre/auth.php
@@@ -1,85 -1,0 +1,87 @@@
 +<?php
 +
 +/**
 + * ownCloud
 + *
 + * @author Jakob Sack
 + * @copyright 2011 Jakob Sack kde@jakobsack.de
 + *
 + * This library is free software; you can redistribute it and/or
 + * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
 + * License as published by the Free Software Foundation; either
 + * version 3 of the License, or any later version.
 + *
 + * This library 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 along with this library.  If not, see <http://www.gnu.org/licenses/>.
 + *
 + */
 +
 +class OC_Connector_Sabre_Auth extends Sabre_DAV_Auth_Backend_AbstractBasic {
 +      /**
 +       * Validates a username and password
 +       *
 +       * This method should return true or false depending on if login
 +       * succeeded.
 +       *
 +       * @return bool
 +       */
 +      protected function validateUserPass($username, $password) {
 +              if (OC_User::isLoggedIn()) {
 +                      OC_Util::setupFS(OC_User::getUser());
 +                      return true;
 +              } else {
 +                      OC_Util::setUpFS();//login hooks may need early access to the filesystem
++                      //setup extra user backends
++                      OC_User::setupBackends();//if you do not want to use Owncloud's integrated login
 +                      if(OC_User::login($username, $password)) {
 +                              OC_Util::setUpFS(OC_User::getUser());
 +                              return true;
 +                      }
 +                      else{
 +                              return false;
 +                      }
 +              }
 +      }
 +
 +      /**
 +       * Returns information about the currently logged in username.
 +       *
 +       * If nobody is currently logged in, this method should return null.
 +       *
 +       * @return string|null
 +       */
 +      public function getCurrentUser() {
 +              $user = OC_User::getUser();
 +              if(!$user) {
 +                      return null;
 +              }
 +              return $user;
 +      }
 +
 +      /**
 +        * Override function here. We want to cache authentication cookies
 +        * in the syncing client to avoid HTTP-401 roundtrips.
 +        * If the sync client supplies the cookies, then OC_User::isLoggedIn()
 +        * will return true and we can see this WebDAV request as already authenticated,
 +        * even if there are no HTTP Basic Auth headers.
 +        * In other case, just fallback to the parent implementation.
 +        *
 +        * @return bool
 +        */
 +      public function authenticate(Sabre_DAV_Server $server, $realm) {
 +
 +              if (OC_User::handleApacheAuth() || OC_User::isLoggedIn()) {
 +                      $user = OC_User::getUser();
 +                      OC_Util::setupFS($user);
 +                      $this->currentUser = $user;
 +                      return true;
 +              }
 +
 +              return parent::authenticate($server, $realm);
 +    }
 +}