I'm really surprised that this isn't builtin to more NLEs. I've tried this in the past, but using SVN (long long ago). At CG/post houses with custom pipeline tools, they have an easy way to version up builtin. With NLEs, it's all up to the editor duplicating timelines. However, with literal EDLs, it's hard with modern editing as so much has to be simplified to satisfy the EDL. I think AE has a version up tool (memory is fuzzy). Even tried using Time Machine backups to roll back to prior versions. All sorts of hacks that I really feel should be built in to software that is known for multiple revisions.