--- a/tests/test-revset.t	Tue Sep 25 16:03:14 2018 -0400
+++ b/tests/test-revset.t	Tue Sep 25 15:27:41 2018 -0400
@@ -1063,6 +1063,14 @@
   8
   9
 
+  $ hg log -T '{rev}\n' -r 'commonancestors(8 + 9)'
+  0
+  1
+  2
+  4
+  8
+  9
+
 test ancestor variants of empty revision
 
   $ log 'ancestor(none())'