SNEAK PREVIEW: This is weird but welcome. CMT, which is taking on the production and presentation of the former ABC series Nashville this season, is offering a sneak preview of the new season, which doesn’t begin officially until January 2017. But the new Nashville season premiere will be two hours long, and CMT is showing only the first half tonight. But it’s still a treat, and it’s still a chance to see how new showrunners Marshall Herskovitz and Ed Zwick, the talented writer-producers behind thirtysomething, will deal with this show now that they’ve inherited it. The last show they did together was the Internet-only series quarterlife, which was wonderful – but that was back in 2008. One of the changes to Nashville this season: the addition of Rhiannon Giddons, lead singer of the fabulous Carolina Chocolate Drops, in her first acting role. For a little preview of the preview, see David Hinckley's All Along the Watchtower.