diff -r 5ef2da00e935 -r e9aadee698cf mercurial/wireprotoframing.py
--- a/mercurial/wireprotoframing.py	Wed Mar 28 13:01:28 2018 -0700
+++ b/mercurial/wireprotoframing.py	Wed Mar 28 13:30:24 2018 -0700
@@ -79,10 +79,12 @@
 
 FLAG_BYTES_RESPONSE_CONTINUATION = 0x01
 FLAG_BYTES_RESPONSE_EOS = 0x02
+FLAG_BYTES_RESPONSE_CBOR = 0x04
 
 FLAGS_BYTES_RESPONSE = {
     b'continuation': FLAG_BYTES_RESPONSE_CONTINUATION,
     b'eos': FLAG_BYTES_RESPONSE_EOS,
+    b'cbor': FLAG_BYTES_RESPONSE_CBOR,
 }
 
 FLAG_ERROR_RESPONSE_PROTOCOL = 0x01