Fix potential NULL pointer dereferencing in ast module
CID 719690
diff --git a/Python/ast.c b/Python/ast.c
index 1b5fa6c..9a0b064 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -535,11 +535,11 @@
     if (!c->c_normalize)
         return 0;
     c->c_normalize_args = Py_BuildValue("(sN)", "NFKC", Py_None);
-    PyTuple_SET_ITEM(c->c_normalize_args, 1, NULL);
     if (!c->c_normalize_args) {
         Py_CLEAR(c->c_normalize);
         return 0;
     }
+    PyTuple_SET_ITEM(c->c_normalize_args, 1, NULL);
     return 1;
 }