Johannes Schindelin [off-list ref] writes:
This is more a drive-by comment, as I have no stake in this, but don't we
already have a more generic solution via `-O<orderfile>`? See
https://git-scm.com/docs/git-diff#Documentation/git-diff.txt--Oltorderfilegt
for details.
The use cases are quite different. This one is meant for a
single-shot use, while orderfile is a more permanent thing.
See https://lore.kernel.org/git/xmqqeehp2jis.fsf@gitster.c.googlers.com/ (local)
and start reading from "I suspect that" for background story.