Re: [PATCH v2 3/3] pretty: add abbrev option to %(describe)

> The %(describe) placeholder by default, like `git describe`, uses a
> seven-character abbreviated commit object name. This may not be
> sufficient to fully describe all commits in a given repository,
> resulting in a placeholder replacement changing its length because the
> repository grew in size.  This could cause the output of git-archive to
> change.
>
> Add the --abbrev option to `git describe` to the placeholder interface
> in order to provide tools to the user for fine-tuning project defaults
> and ensure reproducible archives.
>
> One alternative would be to just always specify --abbrev=40 but this may
> be a bit too biased...
>
> Signed-off-by: Eli Schwartz <eschwartz@archlinux.org>
> ---
> diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
> @@ -222,6 +222,10 @@ The placeholders are:
> +** 'abbrev=<N>': Instead of using the default number of hexadecimal digits
> +   (which will vary according to the number of objects in the repository with a
> +   default of 7) of the abbreviated object name, use <n> digits, or as many digits
> +   as needed to form a unique object name.

> diff --git a/pretty.c b/pretty.c
> @@ -1245,6 +1246,19 @@ static size_t parse_describe_args(const char *start, struct strvec *args)
> +                       case OPT_INTEGER:
> +                               if (match_placeholder_arg_value(arg, option[i].name, &arg,
> +                                                               &argval, &arglen) && arglen) {
> +                                       if (!arglen)
> +                                               return 0;