title: Symfony2 command "doctrine:schema:update" not detect trait file changes used in entities
body: <p>I have a Trait file with shared code between entities. </p>
  
  <p>trait file example:</p>
  
  <pre><code>&lt;?php
  namespace Acme\CmsBundle\Entity;
  
  use Doctrine\ORM\Mapping as ORM;
  
  /**
  * BaseHtml Trait
  *
  */
  trait BaseHtml
  {
  
      /**
      * @var integer
      *
      * @ORM\Column(name="status", type="string", length=20)
      */
      private $status;
  
      /**
      * @var \DateTime
      *
      * @ORM\Column(name="date", type="datetime")
      */
      private $date;
  
      public function setStatus($status)
      {
          $this-&gt;status = $status;
  
          return $this;
      }
  
      public function getStatus()
      {
          return $this-&gt;status;
      }
  
      public function setDate($date)
      {
          $this-&gt;date = $date;
  
          return $this;
      }
  
      public function getDate()
      {
          return $this-&gt;date;
      }
  
  }
  </code></pre>
  
  <p>Entity file example:</p>
  
  <pre><code>&lt;?php
  
  namespace Acme\CmsBundle\Entity;
  
  use Doctrine\ORM\Mapping as ORM;
  
  /**
  * Page
  *
  * @ORM\Table()
  * @ORM\Entity
  * 
  * 
  */
  class Page
  {
  
      use BaseHtml;
  
  
      /**
      * @var integer
      *
      * @ORM\Column(name="id", type="integer")
      * @ORM\Id
      * @ORM\GeneratedValue(strategy="AUTO")
      */
      private $id;
  
      /**
      * @var string
      *
      * @ORM\ManyToOne(targetEntity="Application\Sonata\MediaBundle\Entity\Gallery") 
      */
      private $gallery;
  
  
  
      public function getId()
      {
          return $this-&gt;id;
      }
  
  
      public function setGallery(\Application\Sonata\MediaBundle\Entity\Gallery $gallery)
      {
          $this-&gt;gallery = $gallery;
  
          return $this;
      }
  
  
      public function getGallery()
      {
          return $this-&gt;gallery;
      }
  }
  </code></pre>
  
  <p>But when I modify the annotations of trait file or add new columns and execute "php app/console doctrine:schema:update":</p>
  
  <pre><code>Nothing to update - your database is already in sync with the current entity metadata.
  </code></pre>
  
  <p>I need change manually date modification of all entities files who use traits file for get doctrine:schema:update run properly.</p>
  
  <p>I tried with commands</p>
  
  <pre><code>php app/console doctrine:cache:clear-metadata
  php app/console cache:clear
  </code></pre>
  
  <p>before execute doctrine:schema:update, but without result.</p>
  
  <p>Any idea for don't manually update entities files and doctrine:schema:update detect updates of entities when change traits file, i lost part of advantages of sharing code with traits. </p>