Ivan Drucker did not originally intend for his Raspple II build process to be used by anyone else but him. Moreover, he did not have anything like pi-gen to produce a customized Raspbian distribution with his changes baked in when he designed it.
He used a custom bash history file which is not the most readable thing ever. The goal of this repository is to slowly transform these history files into usable scripts which can be inserted into a bootstrap system like pi-gen or the live image builder for Debian.
In October 2015 when Ivan wrote his email explaining the Raspbian and VirtualBox build processes, the history files were quite different than they are today. Functionally they do the same thing, however in 2015 they were written for Debian/Raspbian Wheezy. They did not support Jessie or systemd in the slightest. Fast forward and these scripts now assume and require systemd and are written for Jessie. These are for the release feature-completed at KansasFest 2016. They could be used with a current Raspbian Jessie release and dropped into NOOBS, which Ivan should be doing soon.
What we're working on is that release + 1.