We don't care about anything older than 5.0 sorry
If you get a desync on the latest 5.0-dev version (with /exactly/ the same settings - it's easy to miss something!), that's a bug we should really fix. Sticking on an ancient, unsupported version will burn you in other ways.
Eh, there are a dozen reasons for desyncing. A bunch of them are in the hands of the user.