local: add error message for cross file system moves

local/local.go

@@ -484,6 +484,7 @@ func (f *Fs) Move(src fs.Object, remote string) (fs.Object, error) {
 	} else if err != nil {
 		// not quite clear, but probably trying to move a file across file system
 		// boundaries. Copying might still work.
+		fs.Errorf(src, "Can't move: %v: trying copy", err)
 		return nil, fs.ErrorCantMove
 	}