diff -r 0132221c25cd -r 876494fd967d tests/test-ancestor.py
--- a/tests/test-ancestor.py	Mon Sep 24 14:46:37 2018 -0700
+++ b/tests/test-ancestor.py	Thu Jan 17 09:17:12 2019 -0800
@@ -123,7 +123,6 @@
             # reference slow algorithm
             naiveinc = naiveincrementalmissingancestors(ancs, bases)
             seq = []
-            revs = []
             for _ in xrange(inccount):
                 if rng.random() < 0.2:
                     newbases = samplerevs(graphnodes)