Inconsistency for napa/node zone when accessing '__dirname' in global module

[fs-eire]

let napaZone = napa.zone.create('test-dirname-zone', { workers: 1 });
let nodeZone = napa.zone.node;

napaZone.broadcast('var getDirname = function () { return __dirname; };');
nodeZone.broadcast('var getDirname = function () { return __dirname; };');

Napa Zone

napaZone.execute("", "getDirname")

This returns the working directory.

Node Zone

nodeZone.execute("", "getDirname")

This throws exception saying that '__dirname' is undefined.

[ghost]

Please fix