old_contents: """celery.backends.cache"""
  from __future__ import absolute_import, unicode_literals
  
  from datetime import timedelta
  
  import django
  from django.utils.encoding import smart_str
  from django.core.cache import cache, get_cache
  
  from celery import current_app
  from celery.utils.timeutils import timedelta_seconds
  from celery.backends.base import KeyValueStoreBackend
  
  # CELERY_CACHE_BACKEND overrides the django-global(tm) backend settings.
  if current_app.conf.CELERY_CACHE_BACKEND:
      cache = get_cache(current_app.conf.CELERY_CACHE_BACKEND)  # noqa
  
  
  class DjangoMemcacheWrapper(object):
      """Wrapper class to django's memcache backend class, that overrides the
      :meth:`get` method in order to remove the forcing of unicode strings
      since it may cause binary or pickled data to break."""
  
      def __init__(self, cache):
          self.cache = cache
  
      def get(self, key, default=None):
          val = self.cache._cache.get(smart_str(key))
          if val is None:
              return default
          else:
              return val
  
      def set(self, key, value, timeout=0):
          self.cache.set(key, value, timeout)
  
  # Check if django is using memcache as the cache backend. If so, wrap the
  # cache object in a DjangoMemcacheWrapper for Django < 1.2 that fixes a bug
  # with retrieving pickled data.
  from django.core.cache.backends.base import InvalidCacheBackendError
  try:
      from django.core.cache.backends.memcached import CacheClass
  except InvalidCacheBackendError:
      pass
  else:
      if django.VERSION[0:2] < (1, 2) and isinstance(cache, CacheClass):
          cache = DjangoMemcacheWrapper(cache)
  
  
  class CacheBackend(KeyValueStoreBackend):
      """Backend using the Django cache framework to store task metadata."""
  
      def __init__(self, *args, **kwargs):
          super(CacheBackend, self).__init__(*args, **kwargs)
          expires = kwargs.get('expires',
                               current_app.conf.CELERY_TASK_RESULT_EXPIRES)
          if isinstance(expires, timedelta):
              expires = int(timedelta_seconds(expires))
          self.expires = expires
  
      def get(self, key):
          return cache.get(key)
  
      def set(self, key, value):
          cache.set(key, value, self.expires)
  
      def delete(self, key):
          cache.delete(key)
  
new_contents: """celery.backends.cache"""
  from __future__ import absolute_import, unicode_literals
  
  from datetime import timedelta
  
  import django
  from django.utils.encoding import smart_str
  from django.core.cache import cache, get_cache
  
  from celery import current_app
  from celery.utils.timeutils import timedelta_seconds
  from celery.backends.base import KeyValueStoreBackend
  
  # CELERY_CACHE_BACKEND overrides the django-global(tm) backend settings.
  if current_app.conf.CELERY_CACHE_BACKEND:
      cache = get_cache(current_app.conf.CELERY_CACHE_BACKEND)  # noqa
  
  
  class DjangoMemcacheWrapper(object):
      """Wrapper class to django's memcache backend class, that overrides the
      :meth:`get` method in order to remove the forcing of unicode strings
      since it may cause binary or pickled data to break."""
  
      def __init__(self, cache):
          self.cache = cache
  
      def get(self, key, default=None):
          val = self.cache._cache.get(smart_str(key))
          if val is None:
              return default
          else:
              return val
  
      def set(self, key, value, timeout=0):
          self.cache.set(key, value, timeout)
  
  # Check if django is using memcache as the cache backend. If so, wrap the
  # cache object in a DjangoMemcacheWrapper for Django < 1.2 that fixes a bug
  # with retrieving pickled data.
  from django.core.cache.backends.base import InvalidCacheBackendError
  try:
      from django.core.cache.backends.memcached import CacheClass
  except (ImportError, InvalidCacheBackendError):
      pass
  else:
      if django.VERSION[0:2] < (1, 2) and isinstance(cache, CacheClass):
          cache = DjangoMemcacheWrapper(cache)
  
  
  class CacheBackend(KeyValueStoreBackend):
      """Backend using the Django cache framework to store task metadata."""
  
      def __init__(self, *args, **kwargs):
          super(CacheBackend, self).__init__(*args, **kwargs)
          expires = kwargs.get('expires',
                               current_app.conf.CELERY_TASK_RESULT_EXPIRES)
          if isinstance(expires, timedelta):
              expires = int(timedelta_seconds(expires))
          self.expires = expires
  
      def get(self, key):
          return cache.get(key)
  
      def set(self, key, value):
          cache.set(key, value, self.expires)
  
      def delete(self, key):
          cache.delete(key)
  
subject: Handle removal of CacheClass