merge: add a --signoff flag
Some projects require every commit, even merges, to be signed off
[*1*]. Because "git merge" does not have a "--signoff" option like
"git commit" does, the user needs to add one manually when the
command presents an editor to describe the merge, or later use "git
commit --amend --signoff".
Help developers of these projects by teaching "--signoff" option to
"git merge".
*1* https://public-inbox.org/git/CAHv71zK5SqbwrBFX=a8-DY9H3KT4FEyMgv__p2gZzNr0WUAPUw@mail.gmail.com/T/#u
Requested-by: Dan Kohn <dan@linuxfoundation.org>
Signed-off-by: Łukasz Gryglicki <lukaszgryglicki@o2.pl>
Signed-off-by: Junio C Hamano <gitster@pobox.com>