Index: Tools/unicode/gencodec.py
===================================================================
--- Tools/unicode/gencodec.py	(revision 86837)
+++ Tools/unicode/gencodec.py	(working copy)
@@ -52,7 +52,7 @@
 
     """
     if not codes:
-        return None
+        return -1
     l = codes.split('+')
     if len(l) == 1:
         return int(l[0],16)
@@ -60,8 +60,8 @@
         try:
             l[i] = int(l[i],16)
         except ValueError:
-            l[i] = None
-    l = [x for x in l if x is not None]
+            l[i] = -1
+    l = [x for x in l if x != -1]
     if len(l) == 1:
         return l[0]
     else:
@@ -113,7 +113,7 @@
     # mappings to None for the rest
     if len(identity) >= len(unmapped):
         for enc in unmapped:
-            enc2uni[enc] = (None, "")
+            enc2uni[enc] = (-1, "")
         enc2uni['IDENTITY'] = 256
 
     return enc2uni
@@ -211,7 +211,7 @@
             (mapkey, mapcomment) = mapkey
         if isinstance(mapvalue, tuple):
             (mapvalue, mapcomment) = mapvalue
-        if mapkey is None:
+        if mapkey == -1:
             continue
         table[mapkey] = (mapvalue, mapcomment)
         if mapkey > maxkey:
@@ -223,11 +223,11 @@
     # Create table code
     for key in range(maxkey + 1):
         if key not in table:
-            mapvalue = None
+            mapvalue = -1
             mapcomment = 'UNDEFINED'
         else:
             mapvalue, mapcomment = table[key]
-        if mapvalue is None:
+        if mapvalue == -1:
             mapchar = UNI_UNDEFINED
         else:
             if isinstance(mapvalue, tuple):