test: fix test failure on linux after edd2fcc

test/simple/test-net-connect-options-ipv6.js

@@ -22,10 +22,18 @@
 var common = require('../common');
 var assert = require('assert');
 var net = require('net');
+var dns = require('dns');
 
 var serverGotEnd = false;
 var clientGotEnd = false;
 
+dns.lookup('localhost', 6, function(err) {
+  if (err) {
+    console.error('Looks like IPv6 is not really supported');
+    console.error(err);
+    return;
+  }
+
   var server = net.createServer({allowHalfOpen: true}, function(socket) {
     socket.resume();
     socket.on('end', function() {
@@ -61,3 +69,4 @@ process.on('exit', function() {
     assert(serverGotEnd);
     assert(clientGotEnd);
   });
+});