title: Nuget doesn't recognize installed packages after upgrade to NuGet 2.7
body: <p>I just upgraded to NuGet 2.7 and followed the <a href="http://docs.nuget.org/docs/workflows/migrating-to-automatic-package-restore" rel="nofollow">Migrate to automatic package restore walkthrough</a>. After that, I noticed that NuGet didn't recognize the installed packages properly:</p>
  
  <ul>
  <li><p>A build didn't download the packages and consequently the build failed.</p></li>
  <li><p>The package was not listed under "installed" when selecting "Manage NuGet Packages" on the project. </p></li>
  <li><p>When browsing for online packages, there was however a green tick on installed packages, so I could not install them, even though the "installed" tab did not list them.</p></li>
  </ul>
  
  <p>I concluded that the packages were only half recognized as installed by NuGet 2.7, so I manually removed one line from the packages.config and then reinstalled that package. This shows an interesting change in the csproj file (diff view):</p>
  
  <pre><code>  -  &lt;Reference Include="xunit, Version=1.9.2.1705, Culture=neutral, PublicKeyToken=8d05b1bb7a6fdb6c, processorArchitecture=MSIL"&gt;
    -    &lt;SpecificVersion&gt;False&lt;/SpecificVersion&gt;
    +  &lt;Reference Include="xunit"&gt;
         &lt;HintPath&gt;..\packages\xunit.1.9.2\lib\net20\xunit.dll&lt;/HintPath&gt;
       &lt;/Reference&gt;
  </code></pre>
  
  <p>The first two lines were replaced by the third. After that, the package was properly installed again.</p>
  
  <p>So how can I get my packages properly installed again, without performing the above procedure for each package on each project?</p>