--- a/mercurial/obsolete.py	Mon Aug 25 18:10:08 2014 +0200
+++ b/mercurial/obsolete.py	Mon Aug 25 18:26:56 2014 +0200
@@ -400,6 +400,9 @@
             self._load(new)
             # new marker *may* have changed several set. invalidate the cache.
             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))
         return len(new)
 
     def mergemarkers(self, transaction, data):