Thanks; that is perfect. I just tried that it works on the root commit in a newly initialized repo.

I will always do this from now on:

  $ git init
  $ git commit --allow-empty -m NIL

Maybe the git maintainers can be persuaded to make a "git init --nil" which does this in one step.

Eh, just make an alias in ~/.gitconfig no need to add more options to git.

That is:

    [alias]
      nilinit = !sh -c 'git init && git commit --allow-empty -m NIL'

And now git nilinit does what you want.

The problem is that what I want is for "git init --nil" to do that, not for some "git nilinit".

Actually, I want "git init" to do that by default!

Every git repo should begin with an empty commit.

In fact, there should be a special SHA built in representing the empty commit; perhaps an all-zero SHA. This object is understood not to occupy any space in the object store beyond its own SHA: you don't look for an all zero SHA in the object space; it just stands for itself.

Then this same can be used as a parent in any orphan branch.

One of the benefits is that this zero SHA is global. And so all git repos have a common ancestor automatically.

If you and I take some code tarball (the same one) and start git repos individually, then we implicitly have a common merge-base: the NIL commit. If I pull from your repo, then we have this:

          your-import <--- your-hacks
        /
     NIL
        \
          my-import <--- my-hacks

your-import and my-import are the same since we imported the same thing. I can just do a "git rebase your-hacks-branch" to transplant my-hacks over your-hacks, implicitly using NIL as the merge-base.

git-subtree already allows for embedding one git repo in another.

https://github.com/git/git/blob/master/contrib/subtree/git-s...

I see the point but not sure I agree that we should treat all git repositories as having a common base commit. Not thought it through however.

I actually put a basic description of what I intend to do with the repo in the message of my empty root commit these days. Helpful for remembering if I lose momentum and come back to it later.

I'd actually love to start doing that with starting a new branch, but I use rebase -i too much and it really really dislikes empty commits in the set you're working on (it just throws them out).