Re: [PATCH v4 32/39] setup: add support for reading extensions.objectformat

> The transition plan specifies extensions.objectFormat as the indication
> that we're using a given hash in a certain repo.  Read this as one of
> the extensions we support.  If the user has specified an invalid value,
> fail.
>
> Ensure that we reject the extension if the repository format version is
> 0.
>
> Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
> ---
> diff --git a/setup.c b/setup.c
> @@ -470,7 +470,16 @@ static int check_repo_format(const char *var, const char *value, void *vdata)
> +               else if (!strcmp(ext, "objectformat")) {
> +                       int format;
> +
> +                       if (!value)
> +                               return config_error_nonbool(var);
> +                       format = hash_algo_by_name(value);
> +                       if (format == GIT_HASH_UNKNOWN)
> +                               return error("invalid value for 'extensions.objectformat'");