I've enabled custom checkout on a few of the sites I manage, but I can't find a "clean" checkout.liquid that matches the default template. The closest I've found are github gists like this one: https://gist.github.com/jhanstra/64feff0df54e7005126474b900b90349
But those don't exactly match what I'm seeing on shops right now, so I assume they're out of date.
Is there any way to find the current checkout.liquid or, better yet, a git repo so I can watch for updates and ensure my custom template doesn't get too far out of sync?
If you're working on shop with access it's pretty easy to create a fresh up to date version. In a theme copy just rename the current file and make a new checkout layout, or delete and make a new one. The file created will be the current version for Plus shops that opt to have checkout.liquid activated.
If you really need one and can't make it yourself I can pop the file in a github repo but it won't be much use to you outside of a Plus environment.
Updated the old repo just in case it's useful: