anchor.diff:  
       Assert.True <| File.Exists ("cptgt" </> "a" </> "samplefile")
   
  -(*
   [<Test>]
   let ``copies fileset flatten``() =
       "." </> ".xake" |> File.Delete
  
positive.code: 
  let TestOptions = {ExecOptions.Default with Threads = 1; Targets = ["main"]; ConLogLevel = Diag; FileLogLevel = Silent}
  
  (*
  [<Test>]
  let ``copies single file``() =
      "." </> ".xake" |> File.Delete
  
negative.code:     }
  
      Assert.True <| File.Exists ("cptgt" </> "samplefile")
  