title: :dependent => :delete on belongs_to doesn't delete owner object
body: <p>I have been checking options of <a href="http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#method-i-belongs_to">belongs_to</a> method and testing following behavior in Rails 3.2.7</p>
  
  <p>As per above link the <code>:dependent</code> option states that</p>
  
  <blockquote>
    <p>If set to :destroy, the associated object is destroyed when this
    object is. If set to :delete, the associated object is deleted without
    calling its destroy method.</p>
  </blockquote>
  
  <p>As I understand the Author should be removed if Post is removed in following case:</p>
  
  <pre><code>class Post &lt; ActiveRecord::Base
    belongs_to :author, :dependent =&gt; :delete
  end
  
  class Author &lt; ActiveRecord::Base
    attr_accessible :name
    has_one :post
  
    before_destroy :log_author_removal
  
    private
      def log_author_removal
        logger.error('Author is getting removed')
      end
  
  end
  </code></pre>
  
  <p>In console:</p>
  
  <pre><code>&gt; Post.first
    Post Load (0.4ms)  SELECT "posts".* FROM "posts" LIMIT 1
   =&gt; #&lt;Post id: 5, title: "Post 5", author_id: 3&gt;
  &gt; p.delete
    SQL (197.7ms)  DELETE FROM "posts" WHERE "posts"."id" = 5
   =&gt; #&lt;Post id: 5, title: "Post 5", author_id: 3&gt; 
  &gt; Author.find(3)
    Author Load (0.5ms)  SELECT "authors".* FROM "authors" WHERE "authors"."id" = ? LIMIT 1  [["id", 3]]
   =&gt; #&lt;Author id: 3, name: "Author 3"&gt; 
  </code></pre>
  
  <p>However calling <code>p.destroy</code> deletes associated author.</p>
  
  <p>Am I misunderstood above quoted statement?</p>