Question

I just got pretty strange result that I can’t explain

I wanted to determine difference between two branches

So i typed

git log master..release1

And I’ve got multiple commits, including let’s say aa11bb22cc33

But then I called

git branch --contains aa11bb22cc33

And I’ve got

release1
* master

How could this happen?!

My git log command by definition should show only those commits that are reachable in release1, but not reachable in master?

I also tried equivalent

git log ^master release1

with the same strange result.

Please explain if you can how is that possible.

P.S. git 1.8.0

Answer 1

Looking through a few man pages, I think it’s something like this: Even though man gitrevisions says that <A>..<B> is “anything reachable from B but not reachable from A”, just like you quoted, this “reachable” is meant in a strict DAG (directed acyclic graph) sense (i.e. “reachable from” means “is ancestor of”).

Indeed the git log manpage states that <A>..<B> “shows only commits between the two commits.” The latter also concurs with how the dotdot operator was explained to me: “Everything in B that’s not also in A” (implying A and B are something like branches, which can “contain” commits).

In the DAG-sense, however, there are no branches, only commits (any branches are only references to commits). So if commit X is “contained in B”, it is actually some ancestor of B, or in other words: it’s reachable from B — because in the Git history graph, every commit has relations (“pointers”, or arrows in a drawn graph) to its ancestor(s).

Hope this helps.

Edit: What I forgot to mention is why your commit shows up in the log but branch –contains shows both master and the other branch. I just thought I did know but turns out i don’t after all. If you post a the git log --oneline --decorate --all output showing the concerned branches, I might be able to update my answer with a more concrete explanation 🙂