I had dubious pleasure of working with similar codebases and devs. I'll remember one of those guys forever, because whenever he wanted to work on a new branch he would clone the repo, make changes to the master branch, and push code to a new repo numbered repo0001, repo002, ... He refused to change his ways, because "I have a PhD so you are wrong".
Another WTF moment was realisation that MS SQL Server does not support BOOLEAN type. That made porting code fun.