// with EAGAIN.
			if pe, ok := err.(*os.PathError); ok {
				err = pe.Err
			}
			if se, ok := err.(syscall.Errno); ok && (se == syscall.EAGAIN || se == syscall.EMFILE) {
				time.Sleep(time.Millisecond)
				continue
			}

			t.Error(err)
			return
		}
		cmds = append(cmds, cmd)
	}

	failures := 0
	for _, cmd := range cmds {
		err := cmd.Wait()
		if err == nil {