gitlab-based_packaging_workflow: Use the same tools used in CI

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

content/guidelines/gitlab-based_packaging_workflow.md

@@ -54,59 +54,55 @@ either boot the Apertis [SDK]( {{< ref "/sdk.md" >}} ) or enter the
 
 ## How to sync an Apertis package with a new version from Debian
 
-1.  Check out the source repository from GitLab
+1.  On GitLab, [fork the
+    project](https://docs.gitlab.com/ce/user/project/repository/forking_workflow.html)
+    to your personal namespace.
 
+1.  Check out the source repository
+
+        GITLAB_USER=${USER}
         UPSTREAM_DISTRIBUTION=buster
-        UPSTREAM_VERSION=2.58.3-2
-        UPSTREAM=http://deb.debian.org/debian/pool/main/g/glib2.0/glib2.0_${UPSTREAM_VERSION}.dsc
+        MIRROR=https://deb.debian.org/debian
         PACKAGE=glib2.0
-        COMPONENT=target
 
-        git clone git@gitlab.apertis.org:pkg/${COMPONENT}/${PACKAGE}
+        git clone git@gitlab.apertis.org:${GITLAB_USER}/${PACKAGE}
         cd ${PACKAGE}
 
-2.  Sync the upstream contents
-
-        git branch debian/${UPSTREAM_DISTRIBUTION} origin
-
-        GBP_CONF_FILES=/etc/git-buildpackage/gbp.conf gbp import-dsc ${UPSTREAM} --debian-branch=debian/${UPSTREAM_DISTRIBUTION} --upstream-branch=upstream/${UPSTREAM_DISTRIBUTION} --no-pristine-tar --allow-unauthenticated
+1.  Only if moving to a new upstream distribution, prepare the upstream base
+    branches using the current upstream branches as a base:
 
-3.  Commit the orig tarball to pristine-lfs
+        UPSTREAM_DISTRIBUTION=bullseye
+        UPSTREAM_BASE=buster
+        git push origin origin/upstream/${UPSTREAM_BASE}:upstream/${UPSTREAM_DISTRIBUTION}
+        git push origin origin/debian/${UPSTREAM_BASE}:debian/${UPSTREAM_DISTRIBUTION}
 
-        #FIXME: We should consider using 'import-tarballs' script instead, which acts nicely on .dsc files
+1.  Sync the upstream contents
 
-        pristine-lfs commit glib2.0_2.58.3.orig.tar.gz
+        apertis-pkg-pull-updates --package=$PACKAGE --upstream=$UPSTREAM_DISTRIBUTION --mirror=$MIRROR
+        git push origin --follow-tags pristine-lfs upstream/${UPSTREAM_DISTRIBUTION} debian/${UPSTREAM_DISTRIBUTION}
 
-4.  Prepare the repository for the merge [by setting up
-    `dpkg-mergechangelogs`](https://manpages.debian.org/testing/dpkg-dev/dpkg-mergechangelogs.1.en.html#INTEGRATION_WITH_GIT)
-    first and then by configuring it in the repository
+1.  Merge the upstream changes
 
-        git config merge.dpkg-mergechangelogs.driver "dpkg-mergechangelogs -m %O %A %B %A"
-        echo 'debian/changelog merge=dpkg-mergechangelogs' > .git/info/attributes
+        PROPOSED_BRANCH=wip/$GITLAB_USER/update-from-${UPSTREAM_DISTRIBUTION}
+        TARGET_BRANCH=apertis/v2021dev1
+        git checkout -b ${PROPOSED_BRANCH} ${TARGET_BRANCH}
+        apertis-pkg-merge-updates --upstream=debian/${UPSTREAM_DISTRIBUTION} --downstream=${PROPOSED_BRANCH}
 
-5.  Merge the upstream changes
+1.  Only if the merge fails, fix the conflicts and continue
 
-        git checkout -b wip/$USER/upstream-sync
+        git status
+        # fix conflicts
+        git merge --continue
+        dch --local co --no-auto-nmu
 
-        git merge --no-commit debian/{UPSTREAM_DISTRIBUTION}
+1.  Check `debian/changelog` and update it if needed by listing all the remaining Apertis changes
 
-        dch -l co
-
-        # in the editor add some contents to the created changelog entry, leaving it UNRELEASED, for instance:
-        #
-        # glib2.0 (2.58.3-2co1) UNRELEASED; urgency=medium
-        #
-        #  * Sync with Debian Buster
-        #  * Remaining Apertis changes:
-        #    - Disable all tests
-
-        git add ./debian/changelog
-
-        git commit --signoff -m "Sync with Debian ${UPSTREAM_DISTRIBUTION} ${PACKAGE} ${UPSTREAM_VERSION}"
+        $EDITOR debian/changelog
+        git commit --signoff --amend debian/changelog
 
-6.  Push your changes for review
+1.  Push your changes for review
 
-        git push origin debian/${UPSTREAM_DISTRIBUTION} debian/${UPSTREAM_VERSION}
+        git push origin --follow-tags pristine-lfs upstream/${UPSTREAM_DISTRIBUTION} debian/${UPSTREAM_DISTRIBUTION}
         git push -o merge_request.create
 
 ## How to work with downstream packaging changes