diff -r ca2d4080a02e -r b8405d739149 mercurial/merge.py
--- a/mercurial/merge.py	Thu Dec 31 13:45:48 2015 -0500
+++ b/mercurial/merge.py	Sat Jan 02 02:13:56 2016 +0100
@@ -559,7 +559,7 @@
 def _checkunknownfile(repo, wctx, mctx, f, f2=None):
     if f2 is None:
         f2 = f
-    return (os.path.isfile(repo.wjoin(f))
+    return (repo.wvfs.isfileorlink(f)
         and repo.wvfs.audit.check(f)
         and repo.dirstate.normalize(f) not in repo.dirstate
         and mctx[f2].cmp(wctx[f]))