Fix the assertion being made - the result is a tuple of lists of RRHeaders, not a tuple of lists of IRecord providers.  Also, there must be a TTL on the record.

git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/branches/secondary-dns-lookup-error-7408@43046 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb