diff -r 1b9b00aca8a3 -r 413b44003462 mercurial/bundle2.py
--- a/mercurial/bundle2.py	Mon Mar 13 21:58:43 2017 -0700
+++ b/mercurial/bundle2.py	Mon Mar 13 12:40:14 2017 -0700
@@ -271,6 +271,8 @@
     def __nonzero__(self):
         return bool(self._sequences)
 
+    __bool__ = __nonzero__
+
 class bundleoperation(object):
     """an object that represents a single bundling process