diff --git a/mercurial/merge.py b/mercurial/merge.py
index 0d3cce1de2331a88479715f4d708a20fba59b46c_bWVyY3VyaWFsL21lcmdlLnB5..fac040b7e82277b765dfeb46561e130f8c63ed3e_bWVyY3VyaWFsL21lcmdlLnB5 100644
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -74,7 +74,10 @@
         fco = octx[ofile]
         fca = self._repo.filectx(afile, fileid=anode)
         r = filemerge.filemerge(self._repo, self._local, lfile, fcd, fco, fca)
-        if not r:
+        if r is None:
+            # no real conflict
+            del self._state[dfile]
+        elif not r:
             self.mark(dfile, 'r')
         return r