Without this patch, I get the following output when running `grunt build`:

```
Jons-MacBook-Pro:webmaker-profile-2 jon$ grunt build
/Users/jon/Sites/webmaker-profile-2/node_modules/grunt/lib/grunt.js
Running "less:production" (less) task
File .static/css/app.ltr.css created: 152.02 kB → 272.84 kB

Running "autoprefixer:src" (autoprefixer) task
File src created.

Running "autoprefixer:dest" (autoprefixer) task
Warning: No source files were found. Use --force to continue.

Aborted due to warnings.
```