#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
 
diff --git a/Demo/rpc/nfsclient.py b/Demo/rpc/nfsclient.py
index c4387b4..09e78dd 100644
--- a/Demo/rpc/nfsclient.py
+++ b/Demo/rpc/nfsclient.py
@@ -129,7 +129,7 @@
         self.unpacker = NFSUnpacker('')
 
     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
 
@@ -170,7 +170,7 @@
             for fileid, name, cookie in entries:
                 list.append((fileid, name))
                 last_cookie = cookie
-            if eof or last_cookie == None:
+            if eof or last_cookie is None:
                 break
             ra = (ra[0], last_cookie, ra[2])
         return list
@@ -184,7 +184,7 @@
     else: filesys = None
     from mountclient import UDPMountClient, TCPMountClient
     mcl = TCPMountClient(host)
-    if filesys == None:
+    if filesys is None:
         list = mcl.Export()
         for item in list:
             print item
diff --git a/Demo/rpc/rpc.py b/Demo/rpc/rpc.py
index 141fe09..0a14bf2 100644
--- a/Demo/rpc/rpc.py
+++ b/Demo/rpc/rpc.py
@@ -264,13 +264,13 @@
 
     def mkcred(self):
         # Override this to use more powerful credentials
-        if self.cred == None:
+        if self.cred is None:
             self.cred = (AUTH_NULL, make_auth_null())
         return self.cred
 
     def mkverf(self):
         # Override this to use a more powerful verifier
-        if self.verf == None:
+        if self.verf is None:
             self.verf = (AUTH_NULL, make_auth_null())
         return self.verf
 
@@ -321,7 +321,7 @@
 def bindresvport(sock, host):
     global last_resv_port_tried
     FIRST, LAST = 600, 1024 # Range of ports to try
-    if last_resv_port_tried == None:
+    if last_resv_port_tried is None:
         import os
         last_resv_port_tried = FIRST + os.getpid() % (LAST-FIRST)
     for i in range(last_resv_port_tried, LAST) + \
@@ -814,7 +814,7 @@
     def session(self):
         call, host_port = self.sock.recvfrom(8192)
         reply = self.handle(call)
-        if reply != None:
+        if reply is not None:
             self.sock.sendto(reply, host_port)