Don't leak fields

Author: johnslavik

Parser/asdl_c.py

@@ -1503,6 +1503,7 @@ def visitModule(self, mod):
 
     int status = Py_ReprEnter((PyObject *)self);
     if (status != 0) {
+        Py_DECREF(fields);
         if (status < 0) {
             return NULL;
         }