try loopback instead of localhost

Author: Vladimir Kotal

plugins/src/test/java/opengrok/auth/plugin/LdapServerTest.java

@@ -80,7 +80,7 @@ public void testSetGetUsername() {
     @Test
     public void testIsReachable() throws IOException, InterruptedException, URISyntaxException {
         // Start simple TCP server on test port.
-        InetAddress localhostAddr = InetAddress.getLocalHost();
+        InetAddress localhostAddr = InetAddress.getLoopbackAddress();
         try (ServerSocket serverSocket = new ServerSocket(0, 1, localhostAddr)) {
             Thread thread = new Thread(() -> {
                 try {