try:
    from local_settings import *
except ImportError:
    pass

INSTALLED_APPS = (...)

from settings.shared import *
INSTALLED_APPS += ('compressor',)

python manage.py --settings=settings.development

DEV_APPS = None
try:
    from local_settings import *
    INSTALLED_APPS += DEV_APPS
except:
    PASS

DEV_APPS = ('compressor',)

from .base_settings import *

INSTALLED_APPS += ('compressor',)