diff --git a/debian/gitlab-ci.yml b/debian/gitlab-ci.yml
index 9150f20cbae2a838185e872dd76f56cf9725ecf6..b3218b24fbfb6db703231c660833db5cd6642ef6 100644
--- a/debian/gitlab-ci.yml
+++ b/debian/gitlab-ci.yml
@@ -2,15 +2,15 @@ variables:
   DEBFULLNAME: "Salsa Pipeline"
   DEBEMAIL: "<salsa-pipeline@debian.org>"
   DEBIAN_FRONTEND: noninteractive
-  WORKING_DIR: ./debian/output
+  WORKING_DIR: $CI_PROJECT_DIR/debian/output
   DEB_BUILD_OPTIONS: "nocheck noautodbgsym"
-  RELEASE: unstable
+  RELEASE: stretch
 
 stages:
   - build
   - test
 
-build package:
+.build: &build
   stage: build
   image: registry.salsa.debian.org/salsa-ci-team/images/gbp
   services:
@@ -19,13 +19,18 @@ build package:
     expire_in: 180 day
     name: "$CI_BUILD_NAME"
     paths:
-        - ${WORKING_DIR}/
+      - ${WORKING_DIR}/
   script:
     - gbp pull --ignore-branch --pristine-tar --track-missing
     - while true; do sleep 600; echo "10 minutes passed" >&2; done & # Progress keeper since build is long and silent
-    - gbp buildpackage --git-ignore-branch --git-export-dir=${WORKING_DIR} -us -uc --git-builder="docker-build.sh registry.salsa.debian.org/salsa-ci-team/images/base:${RELEASE}" | tail -n 10000 # Keep log under 4 MB
+    - gbp buildpackage --git-ignore-branch --git-export-dir=${WORKING_DIR} -us -uc --git-builder="docker-build.sh registry.salsa.debian.org/salsa-ci-team/images/dockerbuilder:${RELEASE}" | tail -n 10000 # Keep log under 4 MB
     - du -shc ${WORKING_DIR}/* # Show total file size of artifacts. Must stay are under 100 MB.
 
+build package stretch:
+  <<: *build
+  variables:
+    RELEASE: stretch
+
 # Autopkgtest must be disabled, because the test 'upstream' will be skipped and
 # thus the command returns exit code 2 and is considered failed by Gitlab CI.
 # Removing 'breaks-testbed' stanza from tests/control will result in that the
@@ -38,14 +43,21 @@ build package:
 #    - apt-get update && apt-get install autopkgtest eatmydata -y --no-install-recommends
 #    - eatmydata autopkgtest ${WORKING_DIR}/*.deb -- null
 
-run lintian:
+.run_lintian: &run_lintian
   stage: test
-  image: registry.salsa.debian.org/salsa-ci-team/images/lintian
+  image: registry.salsa.debian.org/salsa-ci-team/images/lintian:${RELEASE}
   script:
     - apt-get update
     - apt-get install -y dpkg-dev
     - lintian -iI ${WORKING_DIR}/*.changes
 
+run lintian stretch:
+  <<: *run_lintian
+  dependencies:
+    - build package stretch
+  variables:
+    RELEASE: stretch
+
 # Reprotest exceeds the 2 hour timeout limit on Github CI, so results in failure
 # and must be disabled until a quicker (times two) build is possible.
 #run reprotest:
@@ -82,3 +94,32 @@ run lintian:
 #    - piuparts --hard-link -e ${CHROOT_PATH} ${WORKING_DIR}/*.deb
 #  tags:
 #    - privileged
+
+test upgrade stretch:
+  stage: test
+  dependencies:
+    - build package stretch
+  image: debian:stretch
+  artifacts:
+    when: always
+    name: "$CI_BUILD_NAME"
+    paths:
+      - ${WORKING_DIR}/debug
+  script:
+    - cd ${WORKING_DIR} # Don't repeat this step, it's just cd ./debian/output
+    - mkdir debug
+    - dpkg -l | grep -iE '"'"'maria|mysql|galera'"'"' || true
+    - apt-get update
+    - apt-get install -y mariadb-server-10.1 # Debian Stretch has this and other -10.1 packages
+    - service mysql status || true # Always proceed even if init failed
+    - service mysql restart || true
+    - mariadb --skip-column-names -e "select @@version, @@version_comment"
+    - apt-get install -y ./*.deb
+    - mariadb --version
+    - find /var/lib/mysql -ls > debug/var-lib-mysql.list
+    - cp -ra /etc/mysql debug/etc-mysql
+    - service mysql restart || true # Always proceed even if init failed
+    - service mysql status || true
+    - cp -ra /var/log/mysql debug/var-log-mysql
+    - mariadb --skip-column-names -e "select @@version, @@version_comment"
+    - mariadb -e "create database test; use test; create table t(a int primary key) engine=innodb; insert into t values (1); select * from t; drop table t; drop database test;"
diff --git a/debian/libmariadbclient18.lintian-overrides b/debian/libmariadbclient18.lintian-overrides
new file mode 100644
index 0000000000000000000000000000000000000000..ebb95c2c003ec0f3d8f4b0a38f3184ebd06864d9
--- /dev/null
+++ b/debian/libmariadbclient18.lintian-overrides
@@ -0,0 +1,2 @@
+# OK for legacy reasons
+libmariadbclient18: symbols-file-contains-current-version-with-debian-revision on symbol THR_KEY_mysys@libmysqlclient_16 and 396 others