title: VSIX package build failed without showing the reason (Visual Studio bug)
body: <p>I have to enabled diagnostic mode of MSBuild project build output verbosity to see this:</p>
  
  <pre><code>1&gt;Done executing task "EnableExtension" -- FAILED. (TaskId:81)
  1&gt;Done building target "DeployVsixExtensionFiles" in project "myextension.csproj" -- FAILED.: (TargetId:93)
  ...
  1&gt;Build FAILED.
  1&gt;
  1&gt;Time Elapsed 00:00:01.27
  ========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========
  </code></pre>
  
  <p>My problem is I cannot debug the Visual Studio extension package I'm working on, as the build output says something has failed. What's wired, the obj and bin folders with all content inside (including vsix package), has been created. I don't really know what special I've changed, because few hours ago everything was fine. </p>
  
  <p>How can I investigate what has gone wrong ?</p>
  
  <p>Btw: I'm using VS 2012 Premium Update 1</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>I remembered what I've done. While being in debug mode, I entered Tools -> Extensions and Updates, and uninstalled my currently debugged extension (without restarting VS after that operation). Further attempt of debugging (F5 after CLOSING Experimental Instance of VS) results in this mysterious build behavior.</p>