--- a/mercurial/wireprotoserver.py	Tue Mar 13 19:44:59 2018 -0700
+++ b/mercurial/wireprotoserver.py	Mon Mar 19 16:49:53 2018 -0700
@@ -32,7 +32,7 @@
 HGTYPE = 'application/mercurial-0.1'
 HGTYPE2 = 'application/mercurial-0.2'
 HGERRTYPE = 'application/hg-error'
-HTTPV2TYPE = 'application/mercurial-tbd'
+FRAMINGTYPE = b'application/mercurial-exp-framing-0001'
 
 HTTPV2 = wireprototypes.HTTPV2
 SSHV1 = wireprototypes.SSHV1
@@ -336,21 +336,21 @@
         res.setbodybytes(_('invalid wire protocol command: %s') % command)
         return
 
-    if req.headers.get(b'Accept') != HTTPV2TYPE:
+    if req.headers.get(b'Accept') != FRAMINGTYPE:
         res.status = b'406 Not Acceptable'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('client MUST specify Accept header with value: %s\n')
-                           % HTTPV2TYPE)
+                           % FRAMINGTYPE)
         return
 
     if (b'Content-Type' in req.headers
-        and req.headers[b'Content-Type'] != HTTPV2TYPE):
+        and req.headers[b'Content-Type'] != FRAMINGTYPE):
         res.status = b'415 Unsupported Media Type'
         # TODO we should send a response with appropriate media type,
         # since client does Accept it.
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('client MUST send Content-Type header with '
-                           'value: %s\n') % HTTPV2TYPE)
+                           'value: %s\n') % FRAMINGTYPE)
         return
 
     # We don't do anything meaningful yet.