Ævar Arnfjörð Bjarmason [off-list ref] writes:

AFAICT all of the goals you're suggesting here will be even better if
it's commented out, then you will need to edit it, and we'll error out
by default if you don't. Why not use that?

Simply because I doubt that would work.  Doesn't the stripspace on
the log message with unedited comments simply discard the commented
out part and results in a title that is taken from the line that
happens to end up being the first non-blank-non-commented-out line?

The subject you're replacing isn't content-free, it at least includes
the OID, this one doesn't, so you won't see it in --oneline. That's less
useful.

I know.  That is the point; those who choose to use --reference want
to make sure they want to edit out the line that tell them to edit.

quoted

If we leave something like

	# Add one line above and explain not *what* this revert did,
	# but *why* you decided to revert in 50-70 chars.  Did it
	# break something? Was it premature?

	This reverts commit 8aa3f0dc (CI: set CC in MAKEFLAGS directly, 2022-04-21)

presumably, stripspace will make the "This reverts commit ..." the
title of the reverted commit.  It would invite people not to edit it
out out of laziness.  Since the whole point of this change is to
encourage people to describe the reason behind the revert on the
subject line, such an invitation is counter-productive.

If that's the concern we could also comment the "This reverts" line.

That punishes the normal use case where the title is edited and the
body is used to start the message as-is.