Suppose I have a file "ChangeLog" in branch "master". I want to record information about all changes in any branch in this file (in more detail than in a commit message and with other descriptive information).

I git checkout -b revA, perform edits, update ChangeLog and git commit.

I then git checkout -b master. This checkout will replace ChangeLog with the version in branch "master".

What I would like is for ChangeLog to automagically be the most recently modified version irrespective of which branch I've checked out. I don't want to manually merge (or, most likely, forget to merge) ChangeLog from some other branch into my current branch.

I haven't found anything which seems to allow this. Is it possible to do this?