wireprotov2: re-add tuple around `bundle2` check

I stumbled upon this while looking for the current (v1) `capable` method. It
looks like 9c2c77c73f23 accidentally removed the comma, turning the tuple into
a simple parenthesis expression.

This has not been detected since wireproto2 is not in use AFAIK.

Differential Revision: https://phab.mercurial-scm.org/D9518

mercurial/httppeer.py

@@ -895,7 +895,7 b' class httpv2peer(object):'
             return True
 
         # Other concepts.
-        if name in b'bundle2':
+        if name in (b'bundle2',):
             return True
 
         # Alias command-* to presence of command of that name.