OK, every time Gravity Lounge brings the Battlefield Band or Old Blind Dogs to town we write some nonsense about how one or the other is the reigning champion of traditional Scottish music (see Thursday 9/18, for example). It’s tempting to go down that road with The Tannahill Weavers, but we’ll refrain this time. At least you get to see all these guys, even if you never really can be sure who is leading the pack.