diff -r 8475c9bf096d -r df4985497986 mercurial/wireprotoserver.py
--- a/mercurial/wireprotoserver.py	Sun Apr 08 09:45:45 2018 -0700
+++ b/mercurial/wireprotoserver.py	Mon Apr 09 11:52:31 2018 -0700
@@ -831,6 +831,9 @@
     def name(self):
         return wireprototypes.SSHV2
 
+    def addcapabilities(self, repo, caps):
+        return caps
+
 def _runsshserver(ui, repo, fin, fout, ev):
     # This function operates like a state machine of sorts. The following
     # states are defined: