private IEnumerable<string> GetDllsIn(LocalFileSystemDirectory root, DirectoryInfo dir)
{
log.DebugFormat("Getting DLLs from {0} relative to {1}...", dir.FullName, root.AbsolutePath);
return from file in dir.GetFiles("*.dll")
let relPath = GetRelativePath(file.FullName, root)
select relPath;
}