--- a/mercurial/revlog.py	Fri Aug 17 12:54:50 2018 +0900
+++ b/mercurial/revlog.py	Fri Aug 17 13:07:33 2018 +0900
@@ -1109,7 +1109,8 @@
     def nodemap(self):
         if self.index:
             # populate mapping down to the initial node
-            self.rev(self.node(0))
+            node0 = self.index[0][7]  # get around changelog filtering
+            self.rev(node0)
         return self._nodecache
 
     def hasnode(self, node):