It's similar to a Lisp Machine.

Based on a few old mailing list it's apparently only very slightly so, and i'm not dissing emacs, it's just that the people who made lisp os and it's graphical layer really did allow users to augment and interact with most of the system in a very fluid and capable manner. Some examples from that mailing list (thread from the 90s or maybe even 80s) were still not present on a daily basis for code edition / versionning in the 2000s. Makes you wonder

What else?

We're evaluating Basecamp, Asana, Codegiant, and Nuvro.

Gerrit is a bit different from the various GitHub look-alikes. Have you (Jonas) looked into it? Would a Gerrit backend be feasible?

I miss Darcs too. One potential downside of making cherry-picks very easy is that abusing them can bite you: two patches might be independent in terms of conflicts but functionally dependent (e.g., code in patch A calls a function introduced by patch B).

There's a very nice metronome app for iOS and Android called TimeGuru that works along these lines.