--- a/hgext3rd/topic/topicmap.py	Thu Jun 22 15:18:49 2017 +0200
+++ b/hgext3rd/topic/topicmap.py	Fri Jun 23 10:21:37 2017 +0200
@@ -103,7 +103,7 @@
     extensions.wrapfunction(branchmap, 'updatecache', _wrapupdatebmcache)
 
 def _wrapupdatebmcache(orig, repo):
-    previous = repo._autobranchmaptopic
+    previous = getattr(repo, '_autobranchmaptopic', False)
     try:
         repo._autobranchmaptopic = False
         return orig(repo)