Re: [PATCH RFC] git-am: support any number of signatures

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 13, 2014, 17:32 UTC
Message-ID: <xmqqy4x03ecm.fsf@gitster.dls.corp.google.com>
In-Reply-To: <20140613080036.GA2117@redhat.com>

"Michael S. Tsirkin" <mst@redhat.com> writes:

Show 35 quoted lines

> On Thu, Jun 12, 2014 at 12:07:03PM -0700, Junio C Hamano wrote:
>> "Michael S. Tsirkin" <mst@redhat.com> writes:
>> ...
>> > 1.  new parameter am.signoff can be used any number
>> > 	of times:
>> >
>> > [am]
>> > 	signoff = "Reviewed-by: Michael S. Tsirkin <mst@redhat.com>"
>> > 	signoff = "Signed-off-by: Michael S. Tsirkin <mst@redhat.com>"
>> >
>> > 	if set all signatures are picked up when git am -s is used.
>> 
>> How does this interact with the logic to avoid appending the same
>> Signed-off-by: line as the last one the incoming message already
>> has?
>
> Not handled if you have multiple signatures.
> That will have to be fixed.
> Do we only care about the last line?
>
> Signed-off-by: A
> Signed-off-by: B
>
> do we want to add
>
> Signed-off-by: A
>
> or would it be better to replace with
> Signed-off-by: B
> Signed-off-by: A
>
> ?
>
> Current git am will add A twice, I wonder if this is
> a feature or a bug.

This is very much deliberate.

Appending A after existing A and B is meant to record that the patch originated from A, passed thru B possibly with changes by B, came back to A who wants to assert that the result is still under DCO.

The only case we can safely omit appending A's sign-off is when the last one in the chain is by A. Imagine that you had a patch signed off by B, which A may have tweaked and forwarded under DCO with A's sign-off. Such a patch would have sign-off chain B-A.

Now A makes further changes to the patch and says "the further change is also something I am authorized to release as open source" with the "-s" option or some other way. It would not change that A can contribute under DCO if we did not add an extra A after existing B-A sign-off chain in that case.