add this line in vorpal/lib/session.js

```js
  wrapper.args.command = wrapper.command;
```

add that line above this section:

```js
 wrapper.args.command = wrapper.command;

  // Call the root command.
  res = wrapper.fn.call(commandInstance, wrapper.args, function () {
    debugger;
    var argus = util.fixArgsForApply(arguments);
    onCompletion(wrapper, argus[0], argus[1], argus);
  });
```