いま試してみたら、Vagrant 2.0.0はVirtualBox 5.2にまだ対応していないorz

$ vagrant package --base openSUSE
Vagrant has detected that you have a version of VirtualBox installed
that is not supported by this version of Vagrant. Please install one of
the supported versions listed below to use Vagrant:

4.0, 4.1, 4.2, 4.3, 5.0, 5.1

A Vagrant update may also be available that adds support for the version
you specified. Please check www.vagrantup.com/downloads.html to download
the latest version.