Circular requires that work with regular requires do not work with sandboxed-module

[thoughtless]

Node.js supports circular requires
The behavior can be odd or unexpected, but it is supported.

In some cases though, this library is loading these circular requires differently, causing them to fail.

I posted an example of such a situation here: https://github.com/thoughtless/circular_require_demo

Another example is the NPM module aws-sdk. It has a circular require between service.js and core.js.
require("sandboxed-module").require("aws-sdk") will fail.