--- a/mercurial/merge.py	Fri May 12 11:20:25 2017 -0700
+++ b/mercurial/merge.py	Thu May 11 18:38:43 2017 -0700
@@ -1288,7 +1288,7 @@
         progress(_updating, z, item=f, total=numupdates, unit=_files)
         flags, = args
         audit(f)
-        util.setflags(repo.wjoin(f), 'l' in flags, 'x' in flags)
+        repo.wvfs.setflags(f, 'l' in flags, 'x' in flags)
         updated += 1
 
     # the ordering is important here -- ms.mergedriver will raise if the merge