Comment by apetresc

There's an open PR to add 5.1 support, and it seems to just be a bit-for-bit identical copy of the 5.0 code which Vagrant inexplicably requires a separate driver for: https://github.com/mitchellh/vagrant/pull/7574

All the heavy-duty OOP-first power of Ruby at their fingertips, and people still just copy-and-paste massive files to change a version string...