proper support for "isabelle update -D DIR": avoid accidental exclusion of select_dirs (amending e5dafe9e120f);
/* Title: Pure/System/cygwin.scala
Author: Makarius
Cygwin as POSIX emulation on Windows.
*/
package isabelle
import java.io.{File => JFile}
import java.nio.file.Files
import scala.annotation.tailrec
object Cygwin
{
}