Fixed "exists" method.

boards/models.py

@@ -48,7 +48,7 b' class PostManager(models.Manager):'
     def exists(self, post_id):
         posts = Post.objects.filter(id = post_id)
 
-        return len(posts) == 0
+        return len(posts) > 0
 
     def is_admin(self, user, passw):
         return Admins.objects.filter(name = user, password = passw) is not None

boards/tests.py

@@ -22,7 +22,7 b' class BoardTests(TestCase):'
 	
         Post.objects.delete_post(post)
 
-        self.assertTrue(Post.objects.exists(post_id))
+        self.assertTrue(not Post.objects.exists(post_id))
 
     def test_delete_posts_by_ip(self):
         post = self.create_post()
@@ -30,4 +30,4 b' class BoardTests(TestCase):'
 
         Post.objects.delete_posts_by_ip('0.0.0.0')
 
-        self.assertTrue(Post.objects.exists(post_id))
+        self.assertTrue(not Post.objects.exists(post_id))