Subject to the provisions of this Title, the unpaid seller's right of lien or stoppage in transitu is not affected by any sale, or other disposition of the goods which the buyer may have made, unless the seller has assented thereto.
If, however, a negotiable document of title has been issued for goods, no seller's lien or right of stoppage in transitu shall defeat the right of any purchaser for value in good faith to whom such document has been negotiated, whether such negotiation be prior or subsequent to the notification to the carrier, or other bailee who issued such document, of the seller's claim to a lien or right of stoppage in transitu. (n)