title: Build error when dynamic keyword in generic interface
body: <p>I have generic interface:</p>
  
  <pre><code>public interface IItemDownloader&lt;TResult&gt;
  {
     //FROM:  TResult Do&lt;TResult&gt;();
     //TO:
      TResult Do();
  }
  </code></pre>
  
  <p>I have few implementations like this what causing error:</p>
  
  <pre><code>public class DynamicItemDownloader : IItemDownloader&lt;dynamic&gt;
  </code></pre>
  
  <p>When I use it like </p>
  
  <pre><code>using (IItemDownloader&lt;dynamic&gt; d = new DynamicItemDownloader())
  {
      // i get error during build 
      /*
          Cannot implicitly convert type 'DynamicItemDownloader' to 'IItemDownloader&lt;dynamic&gt;'. An explicit conversion exists (are you missing a cast?)
      */
  }
  </code></pre>
  
  <p>Mystery is that when I am using Visual Studio 2013 U5 RC I get this error. When I try to build it by TFS I get the same error.
  When I use Visual Studio 2015 Enterprise I do not get any error and I am able to execute code.
  When I want to have build-able code from VS2013 and TFS I have to use </p>
  
  <pre><code>using (var d = new DynamicItemDownloader())
  {
      // this is buildable from TFS and VS2013 without error
  }
  </code></pre>
  
  <p>It is mystery for me. Know someone why I get this error? Can someone explain where I am doing something wrong?</p>