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

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

On Thu, Sep 25, 2014 at 3:04 AM, Christian Couder
<christian.couder@gmail.com> wrote:
>> To an existing message ends with Michael's Signed-off-by:, if his
>> "git am --trailer arts" is called to add these three and then a
>> Signed-off-by: from him, should it add an extra S-o-b (because his
>> existing S-o-b will no longer be the last one after adding Acked and
>> others), or should it refrain from doing so?  Can you express both
>> preferences?
>
> The default for "trailer.where" is "end", and for "trailer.ifexists"
> it is "addIfDifferentNeighbor".
> That means that by default it will add the four new trailers at the end.
>
> If either "trailer.ifexists" or "trailer.S-o-b.ifexists" is set to
> "addIfDifferent", then only the first 3 new trailers will be added at
> the end. So yes you can express both preferences.

Suppose that the original ends with Sob, and Michael's "am" invokes
interpret-trailers with Acked/Reviewed/Tested/Sob in this order. The first
three are set to addifDifferent and Sob is set to addIfDifferentNeighbor,
which would be the traditional and sensible default.

Now, how is addIfDifferentNeighbor interpreted? Adding the new Sob
with this single request to add these four is done on a message that
has the same Sob at the end (i.e. Neighbor). Does _you_ adding of
Acked/Reviewed/Tested invalidate the Neighbor-ness and you add the
Sob anew?

If that is what happens, it is not a workable workaround to set Sob to
addIfDifferent only for this invocation.

Alternatively, if Neighbor-ness is evaluated first before you add A/R/T
in response to this request, then you'd refrain from adding a duplicate
Sob. It wasn't quite clear from your description what your design was,
and your explanation above is not still clear, at least to me.