[jacobegold]

GitHub actually stores all the data necessary to do this without changing your ref model as the article suggests — even if you force push, it never garbage collects the commits that the branch used to point to.

I work on a tool that includes a UI for diffing versions of a GitHub PR, but you can totally get the same thing via messing with GitHub.com URLs.

[tomasreimers]

Hi! I work with the commenter - for those wondering here's documentation on that feature (pulled off with pretty much only GH data):

https://graphite.dev/docs/pull-request-versions

If people are interested, probably a thing we could do a technical blog post on.

[fahhem]

I agree, we work on Reviewable, which uses those same blobs.

However, we add tags to commits we're referencing, just in case someone at GitHub gets around to implementing garbage collection!

[jacobegold]

They must have refs on the internal git servers -- they need them for the "force pushed from X to Y" timeline events

[bongobingo1]

I've definitely clicked those links through to 404s.

[fahhem]

You're right, though I think that changed recently? I vaguely remember only the last force push showed up, but now I see more than one so :shrug: