a little more fiddling to make flags like 2.x

Include/code.h

@@ -43,7 +43,9 @@ typedef struct {
 #define CO_NOFREE       0x0040
 
 /* These are no longer used. */
+#if 0
 #define CO_GENERATOR_ALLOWED    0x1000
+#endif
 #define CO_FUTURE_DIVISION    	0x2000
 #define CO_FUTURE_ABSOLUTE_IMPORT 0x4000 /* do absolute imports by default */
 #define CO_FUTURE_WITH_STATEMENT  0x8000

Include/pythonrun.h

@@ -10,7 +10,7 @@ extern "C" {
 #define PyCF_MASK (CO_FUTURE_DIVISION | CO_FUTURE_ABSOLUTE_IMPORT | \
                    CO_FUTURE_WITH_STATEMENT | CO_FUTURE_PRINT_FUNCTION | \
                    CO_FUTURE_UNICODE_LITERALS | CO_FUTURE_BARRY_AS_BDFL)
-#define PyCF_MASK_OBSOLETE 0
+#define PyCF_MASK_OBSOLETE (CO_NESTED)
 #define PyCF_SOURCE_IS_UTF8  0x0100
 #define PyCF_DONT_IMPLY_DEDENT 0x0200
 #define PyCF_ONLY_AST 0x0400