Finally after years ;/
The critical part is to separate source code updates as quilt series with
gbp pq but changes to debian/ directory keep as separate patches in
the base branch (not being quilted) !
- https://honk.sigxcpu.org/projects/git-buildpackage/manual-html/gbp.patches.html
- https://www.mail-archive.com/git-buildpackage@lists.sigxcpu.org/msg00097.html
apt-get install build-essential devscripts
git clone salsa
apt-get build-dep rsyslog
# create debian (custom) patchset
git checkout debian/8.2102.0-2+deb11u1
git checkout -b debian/8.2102.0-2+deb11u1+rb3
git status
# unwind quilt serie to temporary branch
gbp pq import
# update source code (eg. README.bodik.md), do not modify `debian/` files
# rebase commits to any desired shape, each commit will finally end up as one quilt patch
# rewind commits back to quilt files
gbp pq export
# commit source code updates as quilt serie patchset
git commit
# update debian/ files separately
git commit
gbp buildpackage --git-export-dir=../build -us -uc --git-debian-branch=debian/8.2102.0-2+deb11u1+rb3