--- a/hgext3rd/evolve/compat.py	Fri Aug 11 11:43:57 2017 +0200
+++ b/hgext3rd/evolve/compat.py	Fri Aug 11 11:55:07 2017 +0200
@@ -152,3 +152,6 @@
         return self.precursors
 
     obsolete.obsstore.predecessors = predecessors
+
+if not util.safehasattr(obsolete, '_computeorphanset'):
+    obsolete._computeorphanset = obsolete.cachefor('orphan')(obsolete._computeunstableset)