mitchellh/boot2docker-vagrant-box — pull request #69 by dduportal (2014-11-04 08:58:54+00:00)
Title: Enabling the default vagrant share while boot2docker 1.3.0 embed vboxsf

Here is the official documentation from b2d : https://github.com/boot2docker/boot2docker#virtualbox-guest-additions.

We just have to remove the line which was disabling the default /vagrant share.