XB is not loading components from base theme

Overview

Experience Builder is not loading components from the active theme's base theme. This is pretty easy to reproduce, and I'm attaching a zip file with a reduced test case.

This is extremely important for me (and likely many theme/site-template devs). We're planning on bundling our shared library of components within a base theme, so they can easily be updated, etc.

Proposed resolution

Let's get dem components loadin'!