Re: Git/Magit: To which branch was a commit was originally committed?

[Daniel Fleischer]

Upon thinking, one cannot answer the question you're asking. This is
because commits do not hold this information; they don't "remember" in
which branch they were. Git history is a graph where commits are nodes.
Branches are labels we stick to specific nodes. When we update, we move
a label forward to another node. That previous node does not "remember"
that a label was used to be attached to it. The answer I gave you a
minute ago only answers the following question: if I start from a given
commit/node and go forward in time, which branches/labels would I meet?
it answers your question only in the simplest cases (no splits) but
hopefully that is what you're looking for.

Best,

-- 

Daniel Fleischer