--- a/hgext3rd/topic/__init__.py	Thu Apr 19 16:07:23 2018 +0200
+++ b/hgext3rd/topic/__init__.py	Thu Apr 19 16:51:53 2018 +0200
@@ -885,7 +885,7 @@
     # create obsmarkers and move bookmarks
     # XXX we should be creating marker as we go instead of only at the end,
     # this makes the operations more modulars
-    compat.cleanupnodes(repo, successors, 'changetopics')
+    scmutil.cleanupnodes(repo, successors, 'changetopics')
 
     # move the working copy too
     wctx = repo[None]