[1.2.X] Tweaked some asserts not present in older unittest or deprecated from...

[1.2.X] Tweaked some asserts not present in older unittest or deprecated from tests added in r15499. Refs #13987

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15525 bcc190cf-cafb-0310-a4f2-bffc1f526a37