[bartread]

Occasionally though, rather than petering out, you get a rage-fork that does something good.

The io.js fork from node back in 2014 or 2015 springs to mind. IIRC there were a bunch of changes/improvements that needed to be made to move node forward and Joyent were dragging their heels (a V8 upgrade might have been one of them but it's been so long I can't remember for sure). Some of the core devs were getting fed up with how long all of this was taking.

So a group of them forked off io.js from node, did the upgrade and a bunch of other improvements, and eventually all of that was folded back into core node, and everyone was happy with the final result.

But I think we could have found ourselves in a world where we'd all be using io.js rather than node had it turned out slightly differently.

[teddyh]

Also the EGCS fork of GCC. That one ended happily, as, IIRC, the EGCS maintainers were assigned (by the GNU project) to be the new official GCC maintainers.

[Izkata]

Beryl forked from Compiz and even though Compiz was the name people knew, Beryl was more popular for a while because it had like 10-20x more functionality out of the box. At some point they merged back together into Compiz Fusion and lost almost all that additional functionality, as well as most of the momentum it had, then was later renamed back to Compiz.