Re: [PATCH v6 4/4] rebase: support --trailer

> From: Li Chen <chenl311@chinatelecom.cn>
>
> Implement a new `--trailer <text>` option for `git rebase`
> (support merge backend only now), which appends arbitrary
> trailer lines to each rebased commit message.
>
> Reject it if the user passes an option that requires the
> apply backend (git am) since it lacks message‑filter/trailer
> hook. otherwise we can just use the merge backend.
>
> Automatically set REBASE_FORCE when any trailer is supplied.
>
> And reject invalid input before user edits the interactive file.
>
> Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
>[snip]
> diff --git a/Documentation/git-rebase.adoc b/Documentation/git-rebase.adoc
> index 005caf6164..4d2fe4be6e 100644
> --- a/Documentation/git-rebase.adoc
> +++ b/Documentation/git-rebase.adoc
> @@ -487,9 +487,16 @@ See also INCOMPATIBLE OPTIONS below.
>  	Add a `Signed-off-by` trailer to all the rebased commits. Note
>  	that if `--interactive` is given then only commits marked to be
>  	picked, edited or reworded will have the trailer added.
> -+
> +
>  See also INCOMPATIBLE OPTIONS below.
>

> +--trailer=<trailer>::
> +       Append the given trailer line(s) to every rebased commit
> +       message, processed via linkgit:git-interpret-trailers[1].
> +       When this option is present *rebase automatically implies*
> +       `--force-rebase` so that fast‑forwarded commits are also
> +       rewritten.
> +
>[snip]