mercurial/obsolete.py

--- a/mercurial/obsolete.py	Mon Aug 25 16:09:18 2014 +0200
+++ b/mercurial/obsolete.py	Mon Aug 25 16:16:01 2014 +0200
@@ -142,10 +142,10 @@
     off = 0
     diskversion = _unpack('>B', data[off:off + 1])[0]
     off += 1
-    if diskversion != _fm0version:
+    if diskversion not in formats:
         raise util.Abort(_('parsing obsolete marker: unknown version %r')
                          % diskversion)
-    return _fm0readmarkers(data, off)
+    return formats[diskversion][0](data, off)
 
 def _fm0readmarkers(data, off=0):
     """Read and enumerate markers from raw data in format version 0"""
@@ -217,6 +217,10 @@
     data.extend(sucs)
     return _pack(format, *data) + metadata
 
+# mapping to read/write various marker formats
+# <version> -> (decoder, encoder)
+formats = {0: (_fm0readmarkers, _fm0encodeonemarker)}
+
 def encodemeta(meta):
     """Return encoded metadata string to string mapping.
 
@@ -438,13 +442,14 @@
             seennodes |= pendingnodes
         return seenmarkers
 
-def _encodemarkers(markers, addheader=False):
+def _encodemarkers(markers, addheader=False, version=_fm0version):
     # Kept separate from flushmarkers(), it will be reused for
     # markers exchange.
+    encodeone = formats[version][1]
     if addheader:
         yield _pack('>B', _fm0version)
     for marker in markers:
-        yield _fm0encodeonemarker(marker)
+        yield encodeone(marker)
 
 
 # arbitrary picked to fit into 8K limit from HTTP server