diff --git a/mercurial/dirstate.py b/mercurial/dirstate.py
--- a/mercurial/dirstate.py
+++ b/mercurial/dirstate.py
@@ -1187,7 +1187,11 @@
         # changes of dirstate out after restoring from backup file
         self.invalidate()
         filename = self._actualfilename(tr)
-        self._opener.rename(backupname, filename, checkambig=True)
+        o = self._opener
+        if util.samefile(o.join(backupname), o.join(filename)):
+            o.unlink(backupname)
+        else:
+            o.rename(backupname, filename, checkambig=True)
 
     def clearbackup(self, tr, backupname):
         '''Clear backup file'''
diff --git a/tests/test-dirstate-backup.t b/tests/test-dirstate-backup.t
--- a/tests/test-dirstate-backup.t
+++ b/tests/test-dirstate-backup.t
@@ -11,9 +11,8 @@
   abort: stdin: no diffs found
   [255]
 
-A dirstate backup is left behind
+No dirstate backups are left behind
 
   $ ls .hg/dirstate* | sort
   .hg/dirstate
-  .hg/dirstate.backup.import.* (glob)