anchor.diff:          let di = getDirectoryInfo localNugetPath root
           let nupkg = findLocalPackage di.FullName packageName version
           
  -        fixDatesInArchive nupkg.FullName
  +        fixArchive nupkg.FullName
           use zipToCreate = new FileStream(nupkg.FullName, FileMode.Open)
           use zip = new ZipArchive(zipToCreate,ZipArchiveMode.Read)
           
  
positive.code:         else
              Directory.CreateDirectory(targetFolder) |> ignore
  
              fixDatesInArchive fileName            
              ZipFile.ExtractToDirectory(fileName, targetFolder)
  
              // cleanup folder structure
  
negative.code:     with
      | exn -> traceWarnfn "Could not fix timestamps in %s. Error: %s" fileName exn.Message
  
  let fixArchive fileName =
      if isMonoRuntime then fixDatesInArchive fileName
  
  let findLocalPackage directory (packageName:PackageName) (version:SemVerInfo) = 
      let v1 = FileInfo(Path.Combine(directory, sprintf "%O.%O.nupkg" packageName version))
      if v1.Exists then v1 else
  