--- a/tests/drawdag.py	Sat May 13 21:30:02 2017 -0400
+++ b/tests/drawdag.py	Wed May 17 10:48:56 2017 -0700
@@ -214,6 +214,9 @@
     def data(self):
         return self._data
 
+    def filenode(self):
+        return None
+
     def path(self):
         return self._path