also handle degenerates better when we blat sequence
also handle degenerates better when we blat sequence

BjornFJohansson/giraffe,addgene/giraffe,BjornFJohansson/giraffe,BjornFJohansson/giraffe,BjornFJohansson/giraffe,addgene/giraffe,BjornFJohansson/giraffe,UndeadBlow/giraffe,addgene/giraffe,addgene/giraffe,UndeadBlow/giraffe