diff -r ef8518f14e4e -r 6370ed6516a6 mercurial/exchange.py
--- a/mercurial/exchange.py	Sun Oct 15 15:21:47 2017 +0200
+++ b/mercurial/exchange.py	Tue Oct 17 15:55:40 2017 +0200
@@ -1785,17 +1785,6 @@
     outgoing = _computeoutgoing(repo, heads, common)
     bundle2.addparttagsfnodescache(repo, bundler, outgoing)
 
-def _getbookmarks(repo, **kwargs):
-    """Returns bookmark to node mapping.
-
-    This function is primarily used to generate `bookmarks` bundle2 part.
-    It is a separate function in order to make it easy to wrap it
-    in extensions. Passing `kwargs` to the function makes it easy to
-    add new parameters in extensions.
-    """
-
-    return dict(bookmod.listbinbookmarks(repo))
-
 def check_heads(repo, their_heads, context):
     """check if the heads of a repo have been modified