Re: [PATCH v2 1/2] rebase doc: document rebase.useBuiltin

> The rebase.useBuiltin variable introduced in 55071ea248 ("rebase:
> start implementing it as a builtin", 2018-08-07) was turned on by
> default in 5541bd5b8f ("rebase: default to using the builtin rebase",
> 2018-08-08), but had no documentation.
> 
> Let's document it so that users who run into any stability issues with
> the C rewrite know there's an escape hatch[1], and make it clear that
> needing to turn off builtin rebase means you've found a bug in git.
> 
> 1. https://public-inbox.org/git/87y39w1wc2.fsf@evledraar.gmail.com/
> 
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>

> ---
>  Documentation/config/rebase.txt | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/Documentation/config/rebase.txt b/Documentation/config/rebase.txt
> index 42e1ba7575..f079bf6b7e 100644
> --- a/Documentation/config/rebase.txt
> +++ b/Documentation/config/rebase.txt
> @@ -1,3 +1,17 @@
> +rebase.useBuiltin::
> +	Set to `false` to use the legacy shellscript implementation of
> +	linkgit:git-rebase[1]. Is `true` by default, which means use
> +	the built-in rewrite of it in C.
> ++
> +The C rewrite is first included with Git version 2.20. This option
> +serves an an escape hatch to re-enable the legacy version in case any
> +bugs are found in the rewrite. This option and the shellscript version
> +of linkgit:git-rebase[1] will be removed in some future release.
> ++
> +If you find some reason to set this option to `false` other than
> +one-off testing you should report the behavior difference as a bug in
> +git.
> +
>  rebase.stat::
>  	Whether to show a diffstat of what changed upstream since the last
>  	rebase. False by default.
> -- 
> 2.19.1.1182.g4ecb1133ce
> 
>