Kill running docker containers left over from a previous job

.buildkite/hooks/post-checkout

@@ -1,6 +1,21 @@
 CI_BUILD_START=$(date +%s)
 export CI_BUILD_START
 
+#
+# Kill any running docker containers, which are potentially left over from the
+# previous CI job
+#
+(
+  containers=$(docker ps -q)
+  if [[ -n $containers ]]; then
+    echo "Killing stale docker containers"
+    docker ps
+
+    # shellcheck disable=SC2086 # Don't want to double quote $containers
+    docker kill $containers
+  fi
+)
+
 # Processes from previously aborted CI jobs seem to loiter, unclear why as one
 # would expect the buildkite-agent to clean up all child processes of the
 # aborted CI job.