All spawners are pig spawner, and all dungeon/mineshaft chests are empty

I created a world in minecraft snapshot 15w50a and I found a dungeon, but instead of a normal spawner it was a pig spawner, and the chests were bot empty. I looked around for another and it was also empty, Then I created a new world and found 2 more empty dungeons, no blaze spanwer in nether fortress, and cave spider spanwers were pig spawners.