Fix test_exceptions

Author: vstinner

Objects/exceptions.c

@@ -84,12 +84,17 @@ BaseException_vectorcall(PyObject *type_obj, PyObject * const*args,
                          size_t nargsf, PyObject *kwnames)
 {
     PyTypeObject *type = _PyType_CAST(type_obj);
-    PyBaseExceptionObject *self;
+    if (!_PyArg_NoKwnames(type->tp_name, kwnames)) {
+        return NULL;
+    }
 
+    PyBaseExceptionObject *self;
     self = (PyBaseExceptionObject *)type->tp_alloc(type, 0);
-    if (!self)
+    if (!self) {
         return NULL;
-    /* the dict is created on the fly in PyObject_GenericSetAttr */
+    }
+
+    // The dict is created on the fly in PyObject_GenericSetAttr()
     self->dict = NULL;
     self->notes = NULL;
     self->traceback = self->cause = self->context = NULL;