#2503 make singletons compared with "is" not == or !=
Thanks to Wummel for the patch
diff --git a/Demo/rpc/mountclient.py b/Demo/rpc/mountclient.py
index 318a9d9..4e8d92a 100644
--- a/Demo/rpc/mountclient.py
+++ b/Demo/rpc/mountclient.py
@@ -100,7 +100,7 @@
     # This function is called to cough up a suitable
     # authentication object for a call to procedure 'proc'.
     def mkcred(self):
-        if self.cred == None:
+        if self.cred is None:
             self.cred = rpc.AUTH_UNIX, rpc.make_auth_unix_default()
         return self.cred