An iconoclastic Americana musician like Robert Earl Keen, who creates music beholden to no specific genre, continues this approach on his "bluegrass" album. Purists might holler when drums appear on certain tracks and Richard Thompson’s classic “52 Vincent Black Lightning” gets a bluegrass makeover, but Keen was never a traditionalist. He’s a musician who puts together songs from his heart. Happy Prisoner features covers with a core of players, including fellow iconoclast Danny Barnes, once of Bad Livers. Together, they treat “East Virginia Blues,” “Long Black Veil,” and “T for Texas” (with Lyle Lovett) as songs worth rearranging and rediscovering.