title: Set Magento block template in layout xml
body: <p>Having trouble setting a block template in Magento's layout xml. I'm attempting to set the template of a child block, not the entire page layout (almost all docs out there explain how to set template of the layout).</p>
  
  <p>Background: I'm <em>updating</em> a layout handle in my custom action, using the <code>&lt;update /&gt;</code> tag in my module's layout xml. </p>
  
  <p>Essentially, I want to reuse the layout and blocks of the built in product view action, but provide custom templates for a few blocks. (Not just overrides, these need to be brand new templates that are only triggered on my custom action and are themselves overrideable).</p>
  
  <p>My layout html:</p>
  
  <pre><code>&lt;?xml version="1.0"?&gt;
  &lt;layout version="0.1.0"&gt;
  &lt;mymodule_product_index&gt;
      &lt;update handle="catalog_product_view" /&gt;
      &lt;reference name="content"&gt;
          &lt;block type="catalog/product_view" 
          name="product.info" output="toHtml" template="mymodule/product.phtml" /&gt;
          &lt;/reference&gt;
  
      &lt;reference name="product.info.bundle"&gt;
          &lt;action method="setTemplate"&gt;&lt;template&gt;mymodule/customtemplate.phtml&lt;/template&gt;&lt;/action&gt;
      &lt;/reference&gt;
  &lt;/mymodule_product_index&gt;
  &lt;/layout&gt;
  </code></pre>
  
  <p>The <code>setTemplate</code> on <code>product.info.bundle</code> never works; it doesn't seem to affect layout at all. I've tried wrapping the <code>&lt;reference&gt;</code> in other <code>&lt;reference&gt;</code> nodes from parent blocks with no effect. Is it possible to replace block templates in this way? I feel that my problem stems from the fact I'm using an <code>&lt;update /&gt;</code>.</p>
  
  <p>By the way, I know my layout xml is being loaded and there are no errors, the rest of the file is working fine, caching is disabled, have cleared cache anyway, etc.</p>