generating ofp versions 1.1 through 1.3
diff --git a/py_gen/templates/const.py b/py_gen/templates/const.py
index c5a0e93..93418a1 100644
--- a/py_gen/templates/const.py
+++ b/py_gen/templates/const.py
@@ -37,7 +37,7 @@
OFP_VERSION = ${version}
:: for (group, idents) in sorted(groups.items()):
-:: idents.sort(key=lambda (ident, value): eval(value))
+:: idents.sort(key=lambda (ident, value): eval(value) if value != 'OFPVID_NONE' else 0)
# Identifiers from group ${group}
:: for (ident, value) in idents:
:: if version == 1 and ident.startswith('OFPP_'):