Parallel forks

Parallel forks

Consider history: XEmacs has been copying source code from Emacs for what -- ten years or so?
(Emacs doesn't take source code back the other way because they want copyright for the FSF.)

I would be sort of surprised if parallel forks weren't the most common kind. If the two projects
are really going in different directions then I could see non-parallel forks, but does that actually
happen in practice?

I think a common result is that one prong of the fork dies or remerges. Remember how egcs
gave gcc a kick in the butt that popped it past the gcc 2.7.2.3 blockage into gcc 2.9x?