--- a/tests/test-ancestor.py	Sat May 06 04:51:25 2017 +0530
+++ b/tests/test-ancestor.py	Fri Feb 10 16:56:29 2017 -0800
@@ -49,7 +49,7 @@
 def buildancestorsets(graph):
     ancs = [None] * len(graph)
     for i in xrange(len(graph)):
-        ancs[i] = set([i])
+        ancs[i] = {i}
         if graph[i] == [nullrev]:
             continue
         for p in graph[i]: