title: Dependencies of references not copied to output directory
body: <p>I have a CommonUtils lib I have built into a dll which I file reference from several of my projects. CommonUtils depends on log4net.dll which was set as a file reference and copy-local=true when CommonUtils.dll was built. log4net.dll and CommonUtils.dll are not in GAC.</p>
  
  <p>Everything works fine in MyWorkingProject where I only have a file reference to CommonUtils.dll - log4net.dll shows up in the output directory (as it is a dependency of CommonUtils.dll but not referenced from MyWorkingProject).
  However if I create a new project to add some unittests: MyWorkingProjectTest and project reference MyWorkingProject and then file reference CommonUtils.dll again here (I want to use some of the CommonUtils) then upon building log4net.dll which is a dependency in both the project reference and in the file reference as well does not get copied to the output directory.</p>
  
  <p>Can anyone clarify what is happening here? Does the compiler not know which of the log4net.dll files it should grab? Is there something I am doing wrong here? Should I do this in some other way for the log4net.dll to get copied explicitly? 
  Does it make any sense that I have to explicitly reference log4net does it?</p>