从DoesNotExist异常实例获取查找参数

这个 Django tutorial 有一节显示了一些代码 DoesNotExist 正在引发异常:

# Request an ID that doesn't exist, this will raise an exception.
>>> Poll.objects.get(id=2)
Traceback (most recent call last):
    ...
DoesNotExist: Poll matching query does not exist. Lookup parameters were {'id': 2}

异常实例上的消息显示用于查找的参数。但我看不到这些参数:

>>> django.get_version()
'1.5.6'
>>> Client.objects.get(pk=2)
Traceback (most recent call last):
    ...
DoesNotExist: Client matching query does not exist.

实际上,这些信息对于我的项目调试日志记录非常有用。为什么我们看不到它,如果可能的话,它怎么能被打开呢?