Only print readyState deprication message once

lib/net.js

@@ -384,9 +384,13 @@ exports.createConnection = function (port, host) {
 };
 
 
+var readyStateMessage;
 Object.defineProperty(Socket.prototype, 'readyState', {
   get: function () {
-    sys.error('readyState is depricated. Use stream.readable or stream.writable');
+    if (!readyStateMessage) {
+      readyStateMessage = 'readyState is depricated. Use stream.readable or stream.writable';
+      sys.error(readyStateMessage);
+    }
     if (this.readable && this.writable) {
       return 'open';
     } else if (this.readable && !this.writable){