Automattic/vip-quickstart — pull request #353 by westonruter (2014-12-15 05:49:44+00:00)
Title: Define pub/twentyfourteen as WP_DEFAULT_THEME for unit tests

Without this, WordPress is by default comes with `twentyfifteen` as the current theme, but this theme isn't installed. In any case, it was already wrong because the default theme was `twentyfourteen` and not `pub/twentyfourteen` as it needs to be in a VIP context.