Fixed randonly failing test.

Sometimes the DNS was returning one IPv4 and one IPv6 address.
Replacing the IPv4 one left as the only valid address the IPv6; but
if IPv6 is not deployed on the network infrastructure, then that will
fail too, causing the test to fail.

jetty-client/src/test/java/org/eclipse/jetty/client/HttpClientTest.java

@@ -897,9 +897,9 @@ public class HttpClientTest extends AbstractHttpClientServerTest
                     @Override
                     public void succeeded(List<InetSocketAddress> result)
                     {
-                        // Replace the first address with an invalid address so that we
+                        // Add as first address an invalid address so that we test
-                        // test that the connect operation iterates over the addresses.
+                        // that the connect operation iterates over the addresses.
-                        result.set(0, new InetSocketAddress("idontexist", 80));
+                        result.add(0, new InetSocketAddress("idontexist", 80));
                         promise.succeeded(result);
                     }