"wmui-base": "git+https://phabricator.wikimedia.org/diffusion/WMUI/wikimedia-ui-base.git#v0.7.1"
which is then saved to lib/wmui-base.less.
According to https://www.npmjs.com/package/wikimedia-ui-base 0.7.1 was never even published to npm.
I noticed this because it's also breaking LibUp.