diff -r 04c319a07c7b -r 2831d918e1b4 mercurial/obsolete.py
--- a/mercurial/obsolete.py	Sun Feb 25 23:08:41 2018 -0500
+++ b/mercurial/obsolete.py	Sun Feb 25 23:09:07 2018 -0500
@@ -656,7 +656,7 @@
             self.caches.clear()
         # records the number of new markers for the transaction hooks
         previous = int(transaction.hookargs.get('new_obsmarkers', '0'))
-        transaction.hookargs['new_obsmarkers'] = str(previous + len(new))
+        transaction.hookargs['new_obsmarkers'] = '%d' % (previous + len(new))
         return len(new)
 
     def mergemarkers(self, transaction, data):