Answer by Emre_U

Restarting Unity works, also you may want to change the Tag if you have already saved the scene and now problem is persisting. Something gets broken when you use tag to find an object and object has an animator and when you mess with mechanim. It is a bug. Because when you change the tag and look for that tag next time same code works perfectly. Though I guess you can avoid it by looking for all objects and then checking if it has (clone) property in name. better yet just change the tag (Unity 5.3 here - the stable built :P )