diff -r 1541e1a8e87d -r aacfca6f9767 mercurial/sshpeer.py
--- a/mercurial/sshpeer.py	Fri Apr 06 22:39:58 2018 -0700
+++ b/mercurial/sshpeer.py	Thu Jan 18 12:54:01 2018 +0100
@@ -168,7 +168,7 @@
 
     Returns a list of capabilities that are supported by this client.
     """
-    protoparams = set()
+    protoparams = {'partial-pull'}
     comps = [e.wireprotosupport().name for e in
              util.compengines.supportedwireengines(util.CLIENTROLE)]
     protoparams.add('comp=%s' % ','.join(comps))