Fix unit test

lib/private/user/manager.php

@@ -165,7 +165,10 @@ class Manager extends PublicEmitter implements IUserManager {
 			}
 		}
 
-		\OC::$server->getLogger()->warning('Login failed: \''. $loginname .'\' (Remote IP: \''. $_SERVER['REMOTE_ADDR'] .'\', X-Forwarded-For: \''. $_SERVER['HTTP_X_FORWARDED_FOR'] .'\')', array('app' => 'core'));
+		$remoteAddr = isset($_SERVER['REMOTE_ADDR']) ? $_SERVER['REMOTE_ADDR'] : '';
+		$forwardedFor = isset($_SERVER['HTTP_X_FORWARDED_FOR']) ? $_SERVER['HTTP_X_FORWARDED_FOR'] : '';
+
+		\OC::$server->getLogger()->warning('Login failed: \''. $loginname .'\' (Remote IP: \''. $remoteAddr .'\', X-Forwarded-For: \''. $forwardedFor .'\')', array('app' => 'core'));
 		return false;
 	}