fix(cluster): fix memory leaking in sendCommand method

Author: luin

lib/cluster/index.js

@@ -406,8 +406,8 @@ Cluster.prototype.sendCommand = function (command, stream, node) {
   if (!node && !command.__is_reject_overwritten) {
     command.__is_reject_overwritten = true;
     var reject = command.reject;
-    var partialTry = _.partial(tryConnection, true);
     command.reject = function (err) {
+      var partialTry = _.partial(tryConnection, true);
       _this.handleError(err, ttl, {
         moved: function (slot, key) {
           debug('command %s is moved to %s', command.name, key);