Disallow keyword args for exceptions.

Lib/test/test_exceptions.py

@@ -296,3 +296,10 @@ for args in exceptionList:
                         ( repr(e), checkArgName,
                             repr(expected[checkArgName]),
                             repr(getattr(e, checkArgName)) ))
+
+try:
+    BaseException(a=1)
+except TypeErrror:
+    pass
+else:
+    raise TestFailed("BaseException shouldn't take keyword args")

Objects/exceptions.c

@@ -32,6 +32,9 @@ BaseException_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
     PyBaseExceptionObject *self;
 
+    if (!_PyArg_NoKeywords("BaseException", kwds))
+        return NULL;
+
     self = (PyBaseExceptionObject *)type->tp_alloc(type, 0);
     /* the dict is created on the fly in PyObject_GenericSetAttr */
     self->message = self->dict = NULL;