While failing tests exit with an exit code > 0, a failing before each hook does exit with code 0 when it fails. Here is an example: <img width="955" alt="bildschirmfoto 2016-11-03 um 17 46 41" src="https://cloud.githubusercontent.com/assets/6912756/19977198/1c1981a8-a1f3-11e6-9fc0-d751949f65f4.png"> Consequently, CI tests can fail without the CI tool noticing it.