Overriding config.toml not working

[HugoKlepsch]

The README says:

Note that the config.toml under root directory of your hugo site will completely override the one in the theme directory, so copy the attributes you want to keep or edit from the theme's config.toml to your site's config.toml.

This doesn't appear to work. One way to reproduce this is to follow the Hugo quick start guide using this theme, then copying the config.toml to the project root and deleting the config.toml in this theme. The project will fail to build.