diff -r 5904511fc9f8 -r bbbbd3c30bfc mercurial/exchange.py
--- a/mercurial/exchange.py	Mon Aug 14 16:26:36 2017 -0700
+++ b/mercurial/exchange.py	Fri Jul 28 22:42:10 2017 -0700
@@ -1168,7 +1168,7 @@
         # deprecated; talk to trmanager directly
         return self.trmanager.transaction()
 
-class transactionmanager(object):
+class transactionmanager(util.transactional):
     """An object to manage the life cycle of a transaction
 
     It creates the transaction on demand and calls the appropriate hooks when