keep the build :green_heart:, #first on 1.8.7 and pg is different

The build only failed for ruby-1.8.7 and pg. The problem was that the statement:

```ruby
author = Author.includes(:comments_with_order_and_conditions, :posts).first
```

resulted in Author with ID 2 where on all other rubies / db-engines Author with ID 1
was retunred. Of course this breaks the assertions.
Merge pull request #9323 from senny/build_fix_from_9252

keep the build :green_heart:, #first on 1.8.7 and pg is different