John Prine: At home with the songwriting legend

It’s been 47 years since John Prine earned his first Grammy nomination for best new artist. Since then, he’s won two. At the age of 72, Prine has never been more popular. His highest charting album yet, “The Tree of Forgiveness,” is up for three awards at Sunday’s Grammys. John Dickerson traveled to Nashville for this extended conversation with the songwriting giant.