Django logging config at the project level. I'd have thought this would work, but instead it's a ValueError

settings.py

# Logging config should be merged with the defaults in 
# django.util.log.configure_logging() which is called 
# by django.setup()
LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'loggers': {}
}
for app in INSTALLED_APPS:
    LOGGING['loggers'][app] = {
        'handlers': ['mail_admins'],
        'level': 'ERROR',
        'propagate': False,
    }

settings_exception

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/path/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/path/site-packages/django/core/management/__init__.py", line 354, in execute
    django.setup()
  File "/path/site-packages/django/__init__.py", line 20, in setup
    configure_logging(settings.LOGGING_CONFIG, settings.LOGGING)
  File "/path/site-packages/django/utils/log.py", line 87, in configure_logging
    logging_config_func(logging_settings)
  File "/path/logging/config.py", line 803, in dictConfig
    dictConfigClass(config).configure()
  File "/path/logging/config.py", line 636, in configure
    '%r: %s' % (name, e))
ValueError: Unable to configure logger 'users': Unable to add handler 'mail_admins': 'mail_admins'