title: ActiveRecord autosave:false doesn't appear to work
body: <p>According to the <a href="http://api.rubyonrails.org/classes/ActiveRecord/AutosaveAssociation.html" rel="nofollow">docs</a>, setting <code>:autosave =&gt; false</code> on an association should NOT save those associations when you save the parent.  This doesn't appear to work for me.  I just created a vanilla Rails 3.0.8 app and here's what I get:</p>
  
  <pre><code>class Foo &lt; ActiveRecord::Base
    has_many :bars, :autosave =&gt; false
    accepts_nested_attributes_for :bars
  end
  
  class Bar &lt; ActiveRecord::Base
    belongs_to :foo
  end
  
  f = Foo.new :name =&gt; 'blah', :bars_attributes =&gt; [{:name =&gt; 'lah'},{:name =&gt; 'lkjd'}]
  f.save
  f.bars
   =&gt; [#&lt;Bar id: 1, name: "lah", foo_id: 1, created_at: "2011-06-20 20:51:02", updated_at: "2011-06-20 20:51:02"&gt;, #&lt;Bar id: 2, name: "lkjd", foo_id: 1, created_at: "2011-06-20 20:51:02", updated_at: "2011-06-20 20:51:02"&gt;]
  </code></pre>
  
  <p>What??  Why did it save the <code>bars</code>?</p>
  
  <p>I feel like I'm taking crazy pills!!  What am I missing?</p>
  
  <p><em>Update: It appears as if <code>accepts_nested_attributes_for</code> automatically saves children, even if they're not built using the nested attributes feature.  It think this is a bug.</em></p>