title: Nuget Package Downloads But Isn't Installed On TFS Build
body: <p>Title pretty much says it all. I have a project which uses some nuget packages. All are downloaded but two of them (HTMLAgilityPack and Newtonsoft) are never installed i.e. the .nupkg file is not extracted, thus, the required .dlls cannot be found and the build fails. Here's the part of the build log file showing when the packages are restored on the build server:</p>
  
  <blockquote>
    <p>Target "RestorePackages: (TargetId:587)" in file "##\nuget.targets" from
    project "##.csproj" (target "ResolveReferences" depends on it): </p>
    
    <p>Task "Exec" skipped, due to false condition;</p>
    
    <p>Task "Exec" (TaskId:360)   Task Parameter:Command="##\nuget.exe" install
    "##\packages.config"
    -source "<a href="https://nuget.org/api/v2/" rel="nofollow">https://nuget.org/api/v2/</a>"  -RequireConsent -solutionDir 
    "##\Sources\" (TaskId:360)   Task
    Parameter:LogStandardErrorAsError=True (TaskId:360) "##\nuget.exe" install
    "##\packages.config"
    -source "<a href="https://nuget.org/api/v2/" rel="nofollow">https://nuget.org/api/v2/</a>"  -RequireConsent -solutionDir 
    "##\Sources\ " (TaskId:360)   </p>
  
  <pre><code>Successfully installed '###.Utilities.Excel 1.0.0.0'. (TaskId:360)   
  Successfully installed '###.Utilities.FileIO 1.0.0.1'. (TaskId:360)   
  Successfully installed '###.Utilities.String 1.0.0.0'. (TaskId:360)   
  All packages listed in packages.config are already installed. 
  </code></pre>
    
    <p>(TaskId:360) Done executing
    task "Exec". (TaskId:360) Done building target "RestorePackages" in
    project "##.csproj".: (TargetId:587)</p>
  </blockquote>
  
  <p>As you can see, HTMLAgilityPack and Newtonsoft are not installed as part of the <em>RestorePackages</em> task. Why would TFS build download but not install these packages?</p>