Generated source tar balls can't be built

There are two different source tarballs offered on the release release page:

• https://gitlab.com/sane-project/backends/uploads/54f858b20a364fc35d820df935a86478/sane-backends-1.0.29.tar.gz
• https://gitlab.com/sane-project/backends/-/archive/1.0.29/backends-1.0.29.tar.bz2

For many downstream projects, a URL like the second is preferable. For the reasons why, please refer to: gitlab-org/gitlab-foss#38830 (closed)

Unfortunately, the second one can't be build, due to bf00b9f4

After the change, autoconf needs a complete git checkout (including .git/*), otherwise git describe does not work.

Autoconf itself does quite some extra work in its repo to avoid the need of git metadata, see autoconf configure.ac and git-version-gen.