Docker detection with docker-machine 0.13

[FatherShawn]

We are using this awesome driver on several Macs. It has been working great for 7-8 months. We now have some new users, who therefore got docker-machine 0.13 when they installed using brew.

On docker-machine start the process ends with an error:
Unable to verify the Docker daemon is listening but in fact it is there. As I do not see error reports at docker-machine nor at boot2docker - could it be something with the driver?

[FatherShawn]

As a test, on the same system, I installed VirtualBox and created a similar machine with that driver. No such error.