wireproto: add media type to version 2 capabilities response This is useful to advertise because servers reject unsupported media types. A client may wish to speak multiple media types and choose the one the server supports. I doubt we'll ever use multiple media types or negotiation in core. But during the course of developing this protocol, I may end up making extensions that backport and forward port protocol support as needed to support Mercurial deploys in the wild. e.g. I may deploy support for an older protocol on a server so old clients can continue using it. It's worth pursuing changing the SSH protocol's upgrade mechanism to support multiple media types as well... Differential Revision: https://phab.mercurial-scm.org/D3299

--- 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():