Revival, Gillian Welch’s 1996 debut, is a cornerstone of Americana, or alt-country as it was called at the time. It raised questions of authenticity—Welch, who grew up in Los Angeles, and guitarist David Rawlings met at Boston’s Berklee College Of Music and were blatantly trafficking in Appalachian folk themes and images—but the stark clarity and world-weary tone sounded perfect. Boots No. 1: The Official Revival Bootleg is a companion piece to Revival on the occasion of its 20th anniversary. It’s a 21-track set of demo and live versions, including eight outtakes. It doesn’t add a lot to our understanding of Revival, however: Many of the arrangements on the T Bone Burnett-produced album were as spare as demos, so to hear Welch and Rawlings work through, say, “Orphan Girl” is to hear a less confident or less well-recorded version of basically the same track. Still, it’s cool to discover the unreleased songs, including Johnny Cash “One Piece At A Time” homage “Dry Town,” and to be reminded of how great Revival is.