Does anyone know how --changed-since works with merge commits? If I have A -> B1 -> B2 -> D -> E and A -> C1 -> C2 -> D -> E and I get the changes from C2 to HEAD, does that include B1 and B2 ?

The implementation calls

git diff C2...HEAD ...

, does that help you answer this? • https://github.com/pantsbuild/pants/blob/9aefe448fa11cf08605a6e73b560605d3c9be48a/src/python/pants/vcs/git.py#L78-L117 • https://github.com/pantsbuild/pants/blob/9aefe448fa11cf08605a6e73b560605d3c9be48a/src/python/pants/vcs/changed.py#L123-L133

That will probably help, but I am a recovering piper user, so if someone actually knows what git does here I'd appreciate knowing

I think yes, it includes B1 & B2