Middleman only builds the first file mentioned in bower.json's main section

I’m not sure if this is intentional. When using Middleman (3.3.12) + Bower, if a Bower component has more than 1 file listed in the main section of bower.json, only the first file gets built.

Example:

The main section of Foundation bower.json specifies 3 files. However during build only the first file gets built/copied (verbose build output).

“css/foundation.css” > build/stylesheets/foundation/css/foundation.css.

It missed “js/fountain.js”. For another package, it similarly misses font files which I need copied to the build folder.

config.rb

sprockets.append_path(File.join "#{root}", "bower_components")
sprockets.import_asset "foundation"

Maybe I’m mis-reading this piece of documentation:

If you tell sprockets just about the name of the component, it will make thos files available which are given in the main-section of the bower.json-file.

By available, does this mean that it would not be copied to the build output, but just be available for a sprockets require? If so then, is there something which would copy assets like fonts, imgs (from standard bower component folders) to the build output. (without having to scan those all bower_components folders to do a import_asset for each font, img.)

A minimal repo to reproduce this problem is here. When running middleman build, I expect to see js/fountain.js get copied (like foundation.css).

Any pointers on this would be much appreciated.