diff -r e2b262e2ee73 -r db58186dd8e3 mercurial/setdiscovery.py
--- a/mercurial/setdiscovery.py	Wed Jan 07 17:17:56 2015 -0800
+++ b/mercurial/setdiscovery.py	Wed Jan 07 17:23:21 2015 -0800
@@ -108,7 +108,7 @@
     always = dag.headsetofconnecteds(nodes)
     if size <= len(always):
         return always
-    sample = set()
+    sample = always
     # update from heads
     _updatesample(dag, nodes, sample, always)
     # update from roots