Re-organized imports, removing a couple that were unused.

import warnings

try:

    set

except NameError:

    from sets import Set as set     # Python 2.3 fallback

from django.conf import settings

from django.db import connection, transaction, IntegrityError

from django.db.models.fields import DateField, FieldDoesNotExist

from django.db.models.fields import DateField

from django.db.models.query_utils import Q, select_related_descend

from django.db.models import signals, sql

from django.dispatch import dispatcher

from django.utils.datastructures import SortedDict

try:

    set

except NameError:

    from sets import Set as set     # Python 2.3 fallback

# Used to control how many objects are worked with at once in some cases (e.g.

# when deleting objects).