Dateformat issue using django basic logging formatter

[Ahn ByungHyun]

I'm using django v1.10.4 with python 3.5.2 and write Logging setting in setting.py.

I faced some problem using log formatter.

I want to present date format of log like '%Y-%m-%d %H:%M:%S.%f%z' but %f is not work.

My formatters setting is like this.

'formatters': {

'verbose': {

'format': '%(levelname)s %(asctime)s %(module)s %(process)d %(thread)d %(message)s',
'datefmt':'%Y-%m-%d %H:%M:%S.%f%z',

},
'simple': {

'format': '%(levelname)s %(message)s'

},

},

The log %(asctime)s is printed "2017-01-05 13:54:24.f+0900"

Is this bug? or intented behavior?