“I cut off my hair and I rode straight away, for that wild unknown country where I could not go wrong.”  So sings Bob Dylan in “Isis.”  It’s a line fitting for the mercurial Dylan, especially in 1975 as he and his merry cohorts – both friends and musicians – embarked on a tour of North American cities large and small on the circus-like Rolling Thunder Revue. Back in 2019, we told you about Rolling Thunder Revue: A Bob Dylan Story by Martin Scorsese.  Part concert document and part mockumentary, the controversial film…