[PATCH 3 of 4 V2] obsolete: use version constants in the format mapping

[Pierre-Yves David]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at fb.com>
# Date 1410908271 25200
#      Tue Sep 16 15:57:51 2014 -0700
# Node ID aeae860293266be3c53587b69961d2aa55ea11c8
# Parent  b844b3a93afe695d712fd002764b8507821c46fe
obsolete: use version constants in the format mapping

diff --git a/mercurial/obsolete.py b/mercurial/obsolete.py
--- a/mercurial/obsolete.py
+++ b/mercurial/obsolete.py
@@ -208,11 +208,11 @@ def _fm0encodeonemarker(marker):
     data.extend(sucs)
     return _pack(format, *data) + metadata
 
 # mapping to read/write various marker formats
 # <version> -> (decoder, encoder)
-formats = {0: (_fm0readmarkers, _fm0encodeonemarker)}
+formats = {_fm0version: (_fm0readmarkers, _fm0encodeonemarker)}
 
 def _readmarkers(data):
     """Read and enumerate markers from raw data"""
     off = 0
     diskversion = _unpack('>B', data[off:off + 1])[0]