--- a/mercurial/lock.py	Mon Oct 14 17:12:59 2013 +0200
+++ b/mercurial/lock.py	Wed Oct 02 21:16:40 2013 +0900
@@ -100,7 +100,7 @@
         """
         try:
             locker = util.readlock(self.f)
-        except OSError, why:
+        except (OSError, IOError), why:
             if why.errno == errno.ENOENT:
                 return None
             raise