diff -r 609606d21765 -r f3407d56a6e8 mercurial/bundle2.py
--- a/mercurial/bundle2.py	Thu Jul 20 01:30:41 2017 -0700
+++ b/mercurial/bundle2.py	Wed Aug 02 03:08:42 2017 +0530
@@ -299,6 +299,10 @@
         self.gettransaction = transactiongetter
         self.reply = None
         self.captureoutput = captureoutput
+        self.hookargs = {}
+
+    def addhookargs(self, hookargs):
+        self.hookargs.update(hookargs)
 
 class TransactionUnavailable(RuntimeError):
     pass