prevert ast errors from being normalized before ast_error_finish is called (closes #15846)
diff --git a/Python/ast.c b/Python/ast.c
index 6faf5b2..3d0e384 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -92,7 +92,15 @@
PyObject *u = Py_BuildValue("zii", errstr, LINENO(n), n->n_col_offset);
if (!u)
return 0;
+ /*
+ * Prevent the error from being chained. PyErr_SetObject will normalize the
+ * exception in order to chain it. ast_error_finish, however, requires the
+ * error not to be normalized.
+ */
+ PyObject *save = PyThreadState_GET()->exc_value;
+ PyThreadState_GET()->exc_value = NULL;
PyErr_SetObject(PyExc_SyntaxError, u);
+ PyThreadState_GET()->exc_value = save;
Py_DECREF(u);
return 0;
}