A join to a union, which produces a subquery

gistfile1.rb

(Blog.where(:user_id => 1) | Blog.where(:public => true)).join(Post).to_sql.should be_like_query(%{
  select t1.id         as t1__id, 
         t1.user_id    as t1__user_id, 
         t1.public     as t1__public, 
         posts.id      as posts__id, 
         posts.blog_id as posts__blog_id 
  from   ((select * 
           from   blogs 
           where  blogs.user_id = :v1) 
          union 
          (select * 
           from   blogs 
           where  blogs.public = :v2)) as t1 
         inner join posts 
           on t1.id = posts.blog_id 
}, :v1 => 1, :v2 => true)