How gets the source tree into the upstream branch?

[smoe]

Hello,

from salsa I am used to git-buildpackage and I assume that the https://github.com/LinuxCNC/linuxcnc-gbp repository is meant to mimic what salsa is typically providing, just now for multiple target distributions.

I am perfectly find with how everything is done, except that I would likely have started out with the regular LinuxCNC release tarballs. But either way, once we have the tarball, how is that sent into the pristine-tar branch and how is that unpacked into the upstream branch? What do I miss?

This creates the tarball

linuxcnc-gbp/debian/README.source

Line 73 in e996bfc

tar --create --xz --exclude=.git --exclude=.github --transform "flags=r;s|^./|linuxcnc-${VERSION}/|" --file ../debian-packaging/linuxcnc_${VERSION}.orig.tar.xz .

and In the lines below bits are merged without that tarball being (visibly to me) being touched.

Please kindly help out with a few comments, or with a missing command.