--- a/tests/test-help.t	Tue Mar 13 20:34:38 2018 +0800
+++ b/tests/test-help.t	Mon Feb 26 20:44:01 2018 +0800
@@ -985,6 +985,8 @@
    debugupgraderepo
                  upgrade a repository to use different features
    debugwalk     show how files match on given patterns
+   debugwhyunstable
+                 explain instabilities of a changeset
    debugwireargs
                  (no help text available)
    debugwireproto