steeve/boot2docker — pull request #137 by aheissenberger (2014-02-06 11:14:00+00:00)
Title: detect if ports needed for SSH and DOCKER are free on localhost

and will stop the creation of the VM

this should also prevent some cases like crash plan using the same port:
https://github.com/steeve/boot2docker/issues/48#issuecomment-34240304