18th album is a mixed bag of long-kicked-around live tunes, new takes on old ideas, and a handful of covers. Rage Against the Machine guitarist and protest-song revivalist Tom Morello is featured throughout. ”American Skin,” written in response to the infamous 1999 killing of an unarmed Trayvon Martin by the NYPD. two punk cover tunes: The Saints’ “Just Like Fire Would” swings like sprightly early-’70s Elvis.