--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/contrib/merge-test-compat.sh	Wed Nov 01 23:57:56 2017 +0100
@@ -0,0 +1,15 @@
+#!/bin/bash
+set -euox pipefail
+
+unset GREP_OPTIONS
+NOTOPIC="--config experimental.topic-mode=ignore"
+
+compatbranches=`hg branches --quiet | grep 'mercurial-' | grep -v ':' | sort -n --reverse`
+prev='stable'
+for branch in $compatbranches; do
+    hg up $branch
+    hg merge $prev
+    hg commit -m "test-compat: merge $prev into $branch"
+    prev=$branch
+done
+