I would like to remind everyone of the time where NodeJS was forked into a more bleeding edge version of Node, and eventually down the line, all the changes were pulled into NodeJS and things were consolidated.
Or XEmacs forking off from Emacs in 1993. Although that didn't so much get subsumed but basically died a decade or so ago when most of the features XEmacs provided had been added to normal Emacs.
Edit: It was iojs
https://news.ycombinator.com/item?id=8694953
https://news.ycombinator.com/item?id=8669557