The slaves have a [default configuration value of 2 CPUs][1]. What if the host only has one? Or even worse, HALF A CPU! What happens then? Obviously, we need to think this thru. The fix could probably be released together with the fix for #1. [1]: https://github.com/martinanderssondotcom/mini-dev/blob/bc892d9f62d1116a8b08ffc26b19a6cb668c0d55/Vagrantfile#L18