title: Referenced project dependency is copying from GAC instead of NuGet package folder
body: <p>I'm having a strange issue where I have a Windows Service project (A) that references another project in the solution (B).  The project B has a reference to a nuget package (in this case, protobuf-net); it is correctly referencing the path in the packages folder.  However, when I build the Windows Service project A, the DLL that gets copied is a different version (which is coming from the GAC).</p>
  
  <p>What's the best way to resolve this, and ensure that it's properly copying the dependency.</p>
  
  <p>I tried deleting the associated folder in the packages folder and then rebuilding Project B; this did result in nuget automatically downloading the files again, however I see that the reference in Visual Studio for Project B was updated to an older version in the GAC.  I had to remove the reference in the packages.config file, and then add it again using nuget to get it to update to using the correct path in the packages folder. </p>