Fix test: this should return 0 not 7, since Arel was ignoring select …

…clause and now it's fixed.

Signed-off-by: José Valim <jose.valim@gmail.com>

activerecord/test/cases/relations_test.rb

@@ -521,7 +521,7 @@ def test_count_explicit_columns
     posts = Post.scoped
 
     assert_equal [0], posts.select('comments_count').where('id is not null').group('id').order('id').count.values.uniq
-    assert_equal 7, posts.where('id is not null').select('comments_count').count
+    assert_equal 0, posts.where('id is not null').select('comments_count').count
 
     assert_equal 7, posts.select('comments_count').count('id')
     assert_equal 0, posts.select('comments_count').count