This line causes tests to fail when they are not being run whilst rooted to the solution (i.e. NCrunch/TeamCity etc).  With NCrunch for example the solution is copied to a separate location and there is no explicit copy of the packages directory (as it is not needed for run time typically).  There are a few ways to solve this, for example adding some assemblies as content and copying them to output, using some of the files in the output location directly etc etc.  Thoughts?