Re: [PATCH] git-commit: don't add multiple Signed-off-by: from the same identity

[Junio C Hamano <gitster@pobox.com>]

If you are trying to avoid a run of Signed-off-by: lines like this:

	Signed-off-by: Original Author <oa@example.com>
	Signed-off-by: First Reviewer <fr@example.com>
	Signed-off-by: Second Reviewer <sr@example.com>
	Signed-off-by: Original Author <oa@example.com>
	Signed-off-by: Subsystem Integrator <si@example.com>

It is not a bug.  If the last signed-off-by is not from
yourself, your signed-off-by is added when you ask with "-s",
and this is very much intentionally done to follow the existing
practice of patch passing done in the kernel community, where
Signed-off-by: was invented (Linus or somebody from the kernel
circle can correct me if I am wrong).

When you are passing patches around, tweaks to the patch
contents can be made.  If your patch comes back to you from the
second reviewer, it is not what you originally sent out.  You
would want to sign it off again.

We have deliberately excluded what your other patch tries to do
for a reason.  Even though these lines are not digitally signed,
the intent of adding a Signed-off-by: line with your name is
that you are certifying its origin, according to the definition
of DCO (see Documentation/SubmittingPatches).  This should be a
conscious act from the signer's part, and making it automatic
with a config variable that you set once and forget makes it
much less meaningful.