Scala parser combinators never use atEnd and sometimes never terminate

Please see code below. It does not terminate even though the expected result is to stop applying rep when reader is depleted.

import scala.io.Source
import scala.util.parsing.combinator.Parsers
import scala.util.parsing.input.Reader
import scala.util.parsing.input.Position

object DemoApp extends App {
    val parsers = new DemoParsers
    val reader = new DemoReader(10)
    val result = parsers.startsWith("s").*(reader)
    Console println result
}

class DemoReader(n: Int) extends Reader[String] {
    def atEnd = n == 0
    def first = "s" + n
    def rest = new DemoReader(n - 1)
    def pos = new Position { def line = 0; def column = 0; def lineContents = first }
}

class DemoParsers extends Parsers {
    type Elem = String
    def startsWith(prefix: String) = acceptIf(_ startsWith prefix)("Error: " + _)
}

scala / bug

Scala parser combinators never use atEnd and sometimes never terminate #5514