title: NuGet Restore Fails when dependency adds a .targets import to the .csproj
body: <p>I ran into an issue recently with NuGet restore.  I added a project dependency (in this case PostSharp) and then enabled restore.  I checked in the source, but not the /packages directory (as I shouldn't needed to....right!).  When TeamCity or another developer grabs the source and runs MsBuild, they receive the following error: </p>
  
  <pre><code>C:\TeamCity\buildAgent\work\e374975c0264c72e\ProjectName\ProjectName.csproj(70, 3): error MSB4019: The imported project "C:\TeamCity\buildAgent\work\e374975c0264c72e\packages\PostSharp.2.1.5.1\tools\PostSharp.targets" was not found. Confirm that the path in the &lt;Import&gt; declaration is correct, and that the file exists on disk.
  </code></pre>
  
  <p>The problem is, NuGet hasn't run yet to restore/download PostSharp or it's .targets file.  This feels like a NuGet bug to me, but wanted to see if others have this same issue.</p>
  
  <p>Anybody have this issue or know the resolution.  Yes, I could check-in the /packages directory, but then why use NuGet at all?  </p>