title: Ember.js {{render}} helper model not correctly set
body: <p>I ran in a strange issue. I have an Article template. Within the article template I call a <code>{{render "category/new" category}}</code>.</p>
  
  <p>However when saving the new Category trough an action the wrong model is used. When I change it to <code>{{render "category/new" this}}</code> it uses the Article model. When I leave the model part empty it does also not work.</p>
  
  <p>The <strong>Template</strong>:</p>
  
  <pre><code>&lt;script type="text/x-handlebars" data-template-name="article"&gt;
      ((...))
      {{render "category/new" category}} // calls the popup for adding a new category
      ((...))
  &lt;/script&gt;
  
  &lt;!-- popups --&gt;
  &lt;script type="text/x-handlebars" data-template-name="category/new"&gt;
      &lt;div class="popup"&gt;
          &lt;h2&gt;Add new category&lt;/h2&gt;
  
          Name: {{input type="text" value=name}}&lt;br /&gt;
          Image: {{view App.UploadFile name="image" file=image }}&lt;img {{bind-attr src=image}}&gt;&lt;br /&gt;
          Category-parent: {{input value=categoryRelation}}&lt;br /&gt;
  
          &lt;button {{action 'saveCategory'}}&gt;Save&lt;/button&gt;
          &lt;/div&gt;
  &lt;/script&gt;
  </code></pre>
  
  <p>The <strong>Router</strong>:</p>
  
  <pre><code>// both routes have the render called, it uses the same template
  this.resource('article', {path: '/article/:id'}); 
  this.resource('article.new', {path: "/article/new"});
  </code></pre>
  
  <p>The <strong>Model</strong>:</p>
  
  <pre><code>App.Category = DS.Model.extend({
      name: DS.attr('string'),
      image: DS.attr('string'),
      categoryRelation: DS.belongsTo('category')
  });
  
  App.Article = DS.Model.extend({
      name: DS.attr('string'),
      category: DS.hasMany('category')
  )};
  </code></pre>
  
  <p>The <strong>Controller</strong>:</p>
  
  <pre><code>App.CategoryNewController = Ember.ObjectController.extend({
      actions: {
          saveCategory: function () {
              console.log('CategoryNewController saveCategory action'); // gets called
              console.log(this.get('model')); // the wrong one
              this.get('model').save(); // saves all categories when using {{render "category/new" category}} 
          }
      }
  });
  </code></pre>
  
  <p>Please note, there is no route for Category/new because it is not needed for the {{render}} helper. See: <a href="http://emberjs.com/guides/templates/rendering-with-helpers/#toc_specific" rel="nofollow">http://emberjs.com/guides/templates/rendering-with-helpers/#toc_specific</a> (see table at the bottom of the page)</p>