[PATCH 5 of 6] revlog: remove _chunkbase since it is no longer used

[Siddharth Agarwal]

# HG changeset patch
# User Siddharth Agarwal <sid0 at fb.com>
# Date 1378533933 25200
#      Fri Sep 06 23:05:33 2013 -0700
# Node ID 8c45bfd4369fc7075fb2a2aca7cea6f492bd7782
# Parent  59e9548119a2921c1c4c96dff96cd303eb19fd77
revlog: remove _chunkbase since it is no longer used

This was introduced in 2011 for the lwcopy feature but never actually got used.
A similar hook can easily be reintroduced if needed in the future.

diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -883,9 +883,6 @@
 
         return l
 
-    def _chunkbase(self, rev):
-        return self._chunk(rev)
-
     def _chunkclear(self):
         self._chunkcache = (0, '')