--- a/hgext3rd/evolve/compat.py	Fri Jul 14 07:19:15 2017 +0530
+++ b/hgext3rd/evolve/compat.py	Fri Jul 21 09:50:26 2017 +0200
@@ -8,7 +8,8 @@
 
 from mercurial import (
     hg,
-    obsolete
+    obsolete,
+    util,
 )
 
 try:
@@ -23,7 +24,7 @@
 
 eh = exthelper.exthelper()
 
-if not hasattr(hg, '_copycache'):
+if not util.safehasattr(hg, '_copycache'):
     # exact copy of relevantmarkers as in Mercurial-176d1a0ce385
     # this fixes relevant markers computation for version < hg-4.3
     @eh.wrapfunction(obsolete.obsstore, 'relevantmarkers')