--- a/mercurial/revlog.py	Wed Oct 03 13:57:42 2018 -0700
+++ b/mercurial/revlog.py	Fri Oct 12 16:19:21 2018 +0200
@@ -1937,6 +1937,11 @@
         self.index.append(e)
         self.nodemap[node] = curr
 
+        # Reset the pure node cache start lookup offset to account for new
+        # revision.
+        if self._nodepos is not None:
+            self._nodepos = curr
+
         entry = self._io.packentry(e, self.node, self.version, curr)
         self._writeentry(transaction, ifh, dfh, entry, deltainfo.data,
                          link, offset)