Random tweaks to sync-from-debian

Some things I came across while using it

sync-from-debian

@@ -192,10 +192,10 @@ function push()
     local pt_opt
 
     git checkout "rel-${PHOSH_UNDERSCORE_VERSION}"
-    gbp buildpackage --git-ignore-new --git-dist="${PUREOS_DIST}"
+    gbp buildpackage --git-ignore-new --git-pbuilder --git-dist="${PUREOS_DIST}" -nc
 
     pt_opt="--no-pristine-tar"
-    if [ "$(gbp config push.pristine-tar)" == "True" ]; then
+    if [[ "$(gbp config push.pristine-tar)" =~ ^[Tt]rue$ ]]; then
         if git log --pretty='%P' -n 1 pristine-tar | grep -qsE '^[0-9a-f]{40} [0-9a-f]{40}'; then
             log info "Head of Pristine-tar branch is merge commit, pushing with git"
             pt_opt="--no-pristine-tar"
@@ -216,7 +216,7 @@ function release()
    local DIST
    local VERSION
 
-   gbp dch --local=pureos --distribution="${PUREOS_DIST}" -R -a --dch-opt=--force-distribution -- debian/
+   gbp dch --debian-branch="rel-${PHOSH_UNDERSCORE_VERSION}" --git-author --local=pureos --distribution="${PUREOS_DIST}" -R -a --dch-opt=--force-distribution -- debian/
    dch -a "Upload to ${PUREOS_DIST}"
 
    DIST="$(dpkg-parsechangelog | awk "/^Distribution:/{ print \$2; }")"
@@ -290,7 +290,7 @@ function build()
     gbp pull
     # TODO: we'd better use the --profile=pureos but that is severely outdated in Debian
     # shellcheck disable=SC2016
-    gbp buildpackage --git-pbuilder --git-dist="${PUREOS_DIST}" --git-postbuild='lintian --suppress-tags bad-distribution-in-changes-file $GBP_CHANGES_FILE'
+    gbp buildpackage --git-pbuilder --git-dist="${PUREOS_DIST}" --git-postbuild='lintian --suppress-tags bad-distribution-in-changes-file $GBP_CHANGES_FILE' -nc
 
     log info "Finished build step"
     find_stagenum "${FUNCNAME[0]}" > "${STAGE_FILE}"
@@ -429,6 +429,10 @@ Push to git remote I<remote> instead of I<purism+rw>.
 Start at the given stage instead of the beginning or the last failed
 one.
 
+=item I<version>
+
+The upstream version (i.e. without Debian revision) to import the packaging for.
+
 =back
 
 =head1 Repository setup
@@ -443,7 +447,28 @@ The script assumes the following repository setup:
 tracks the packaging branch as well as the I<upstream> and I<pristine-tar>
 branch.
 
-=item * The remote tracking packaging in Debian is called I<salsa>
+=back
+
+=head1 Additional setup
+
+=over
+
+=item * Setting up chroot for pbuilder:
+
+The script does a final build in a clean chroot using git-pbuilder
+during the I<build> stage. You can create the chroot with
+
+DIST=byzantium git-pbuilder create --mirror=https://repo.pureos.net/pureos
+
+=item * Automatically resolve merge conflicts in the changelogs:
+
+Whenever we backport from Debian git-merge(1) will alert us to
+a conflict in I<debian/changelog> because both Debian and us have
+changed this file. To avoid tedious manual (and potentially error-prone)
+work it is recommended to register dpkg-mergechangelog(8) as a merge driver.
+See the I<INTEGRATION WITH GIT> section of its manual to learn how.
+
+The resulting changelog will preserve both downstream and Debian changes.
 
 =back