IBM Smalltalk (now owned / supported by Instantiations) and ParcPlace Smalltalk both had a revision control system called ENVY. It maintained a separate databa

IBM Smalltalk (now owned / supported by Instantiations) and ParcPlace Smalltalk both had a revision control system called ENVY. It maintained a separate database that contained all the different versions of source for all your projects, and had a system for building up a new image containing the versions you wanted. I used to build a new image from scratch every morning before I started work, so I knew I had the current latest code. It was the best version control system I've ever used.