#2503 make singletons compared with "is" not == or !=
Thanks to Wummel for the patch
diff --git a/Lib/plat-os2emx/pwd.py b/Lib/plat-os2emx/pwd.py
index 95d766a..ceb92d9 100644
--- a/Lib/plat-os2emx/pwd.py
+++ b/Lib/plat-os2emx/pwd.py
@@ -167,7 +167,7 @@
     while 1:
         entry = passwd.readline().strip()
         if len(entry) > 6:
-            if sep == None:
+            if sep is None:
                 sep = __get_field_sep(entry)
             fields = entry.split(sep)
             for i in (2, 3):