diff --git a/.gitlab.mk b/.gitlab.mk
index cb66df4c2cd31980a43b2fd19d3a9fe114a9c215..bf64df88a4d1800b123debecd40fabc129a660d0 100644
--- a/.gitlab.mk
+++ b/.gitlab.mk
@@ -52,7 +52,7 @@ export DEBIAN_STRETCH_DOCKERFILE
 define DEBIAN_BUSTER_DOCKERFILE
 FROM packpack/packpack:debian-buster
 COPY .travis.mk .
-RUN make -f .travis.mk deps_buster_clang_8
+RUN make APT_EXTRA_FLAGS="--allow-releaseinfo-change-version --allow-releaseinfo-change-suite" -f .travis.mk deps_buster_clang_8
 endef
 export DEBIAN_BUSTER_DOCKERFILE
 
diff --git a/.travis.mk b/.travis.mk
index 4e43ad6f37a4ec0dc481f508e3f938f6dd10fa37..a816d17db9cede415f7c008bb70c1321cd2781fd 100644
--- a/.travis.mk
+++ b/.travis.mk
@@ -45,6 +45,18 @@ docker_%:
 
 # Depends
 
+# When dependencies in 'deps_debian' or 'deps_buster_clang_8' goal
+# are changed, push a new docker image into GitLab Registry using
+# the following command:
+#
+# $ make GITLAB_USER=foo -f .gitlab.mk docker_bootstrap
+#
+# It is highly recommended to only add dependencies (don't remove
+# them), because all branches use the same latest image and it is
+# often that a short-term branch is based on non-so-recent master
+# commit, so the build requires old dependencies to be installed.
+# See ce623a23416eb192ce70116fd14992e84e7ccbbe ('Enable GitLab CI
+# testing') for more information.
 deps_debian:
 	apt-get update ${APT_EXTRA_FLAGS} && apt-get install -y -f \
 		build-essential cmake coreutils sed \