If the VirtualBox guest property /VirtualBox/GuestInfo/Net/1/V4/IP returns an IP address ending in .1, raise an error. This addresses an issue that was revealed as an NFS error, where Vagrant was creating an exports file with the wrong IP address. This was thought to be caused by the presence of a docker0 interface, but it manifested itself even without Docker installed. This issue is difficult to reproduce, but hopefully this PR will get us closer to the root cause.
Vagrant Core Plugins
These are plugins that ship with Vagrant. Vagrant core uses its own plugin system to power a lot of the core pieces that ship with Vagrant. Each plugin will have its own README which explains its specific role.