merge: use util.unlinkpath for removing moved files

- more like how removed files are removed.

mercurial/merge.py

@@ -367,7 +367,7 b' def applyupdates(repo, actions, wctx, mc'
         if os.path.lexists(repo.wjoin(f)):
             repo.ui.debug("removing %s\n" % f)
             audit(f)
-            os.unlink(repo.wjoin(f))
+            util.unlinkpath(repo.wjoin(f))
 
     numupdates = len(actions)
     for i, a in enumerate(actions):