lazyindex fix, make load handle negative indexes properly.

mercurial/revlog.py

@@ -98,6 +98,8 b' class lazyindex:'
     def __len__(self):
         return len(self.p.index)
     def load(self, pos):
+        if pos < 0:
+            pos += len(self.p.index)
         self.p.load(pos)
         return self.p.index[pos]
     def __getitem__(self, pos):