Fixed #7978 -- Modified the contrib.sites tests to guarantee the initial...

Fixed #7978 -- Modified the contrib.sites tests to guarantee the initial conditions of the test match meet the requirements of the test. Thanks to Evan Schulz for the report and fix.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8160 bcc190cf-cafb-0310-a4f2-bffc1f526a37