diff -r fe8c6f9f2914 -r b2fa1591fb44 mercurial/wireprotov2server.py
--- a/mercurial/wireprotov2server.py	Fri Apr 13 12:31:34 2018 -0700
+++ b/mercurial/wireprotov2server.py	Fri Apr 13 12:31:56 2018 -0700
@@ -385,6 +385,7 @@
     caps = {
         'commands': {},
         'compression': compression,
+        'framingmediatypes': [FRAMINGTYPE],
     }
 
     for command, entry in wireproto.commandsv2.items():