SFTriStar/FlickrPick something hoppy to go with that crawfish. If you missed the two previous Louisiana Crawfish Boils at Magnolia Pub & Brewery (398 Haight at Masonic), it's not too late to go all backwoods Cajun. The third and final boil happens next Tuesday, June 16, just in time for the summer San Francisco is destined to miss. Magnolia owner Dave McLean said he's flying the crawfish in from Louisiana the day of the event (we know, locavores, it ain't pretty) to sell by the pound ($9 per) fr