diff -r f66be4caeaab -r 4e6dc34b5d7a mercurial/exchange.py
--- a/mercurial/exchange.py	Thu Jun 22 01:29:07 2017 +0530
+++ b/mercurial/exchange.py	Thu Jun 22 03:10:24 2017 +0530
@@ -1582,6 +1582,7 @@
 
     Returns an iterator over raw chunks (of varying sizes).
     """
+    kwargs = pycompat.byteskwargs(kwargs)
     usebundle2 = bundle2requested(bundlecaps)
     # bundle10 case
     if not usebundle2: