当django中出现回溯错误时，我会在stdout中得到2次日志

Traceback (most recent call last):
  File "path/to/your/file.py", line X, in your_function
    # Your code here
  File "path/to/another/file.py", line Y, in another_function
    # Your code here
  ...
  File "path/to/django/core/handlers/exception.py", line Z, in inner
    # Your code here
ExceptionType: Error message

python manage.py runserver 2> /dev/null

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'handlers': {
        'file': {
            'level': 'ERROR',
            'class': 'logging.FileHandler',
            'filename': '/path/to/your/log/file.log',
        },
    },
    'loggers': {
        'django': {
            'handlers': ['file'],
            'level': 'ERROR',
            'propagate': True,
        },
    },
}