title: Updating Visual Studio 2015 extensions end up disabled
body: <p>I have a machine with seems to repeat the following pattern with VS2015 (including all patches).</p>
  
  <ol>
  <li>Install an extension and it's fine, works perfectly.</li>
  <li>The developer of the extension releases a new update.</li>
  <li>Update extension, which means VS2015 needs to be restarted.</li>
  <li>Restart VS2015, look in the extensions and notice that the (updated) extension is now disabled.</li>
  </ol>
  
  <p>I've tried clearing the MEF cache, but that doesn't seem to help. The only way I've found to resolve this is to </p>
  
  <ol>
  <li>Delete the extension</li>
  <li>Restart VS2015</li>
  <li>Notice the extension is still there as disabled</li>
  <li>Delete it again</li>
  <li>Restart VS2015 (it's now removed)</li>
  <li>Install the extension from fresh from the Extension manager.</li>
  </ol>
  
  <p>I have another machine which doesn't experience this, and also the activity.xml file doesn't get updated unless there is a loading issue (where you get the error pop-up).</p>
  
  <p>The first time I noticed this was when I installed Mads Kristensen's Web extensions pack (which included all of his components) and caused all the pre-installed components to be disabled, so I uninstalled that and deleted all the components that were bundled under that, as it looked like it didn't detect the component were already there and created a duplicate behind the scenes, but now it seems this is happening for all 3rd party components.</p>
  
  <p>Has anyone got any ideas what I can try to resolve this and possibly what could be causing this?</p>
  
  <p>I'm hoping there is a file somewhere in the VS folder that is logging the issue.</p>