--- a/mercurial/help/internals/wireprotocol.txt	Wed May 03 10:30:57 2017 -0700
+++ b/mercurial/help/internals/wireprotocol.txt	Wed May 03 14:07:14 2017 -0700
@@ -632,6 +632,9 @@
 branches
 --------
 
+(Legacy command used for discovery in old clients. Clients with ``getbundle``
+use the ``known`` and ``heads`` commands instead.)
+
 Obtain ancestor changesets of specific nodes back to a branch point.
 
 Despite the name, this command has nothing to do with Mercurial named branches.