Fixes #127 - socket is closed issue with pools

lib/client/client.js

@@ -691,6 +691,9 @@ Client.prototype.unbind = function unbind(callback) {
     return callback();
 
   var req = new UnbindRequest();
+  if (this.socket.listeners('error').length === 0) {
+    this.socket.once('error', function(){});
+  }
   return this._send(req, 'unbind', null, callback);
 };