Revert the removal of an unused import (in [14175]) that was referenced in...

Revert the removal of an unused import (in [14175]) that was referenced in documentation. Thanks for noticing, clong.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14359 bcc190cf-cafb-0310-a4f2-bffc1f526a37