nixosTests.tigervnc: fix test

    server.succeed("Xvnc -geometry 720x576 :1 -PasswordFile vncpasswd >&2 &")

    server.wait_until_succeeds("nc -z localhost 5901", timeout=10)

    server.succeed("DISPLAY=:1 xwininfo -root | grep 720x576")

    server.execute("DISPLAY=:1 display -size 360x200 -font sans -gravity south label:'HELLO VNC WORLD' >&2 &")

    server.execute("DISPLAY=:1 display -size 360x200 -font sans -gravity south label:'HELLO VNC' >&2 &")

    client.wait_for_x()

    client.execute("vncviewer server:1 -PasswordFile vncpasswd >&2 &")

    client.wait_for_window(r"VNC")

    client.screenshot("screenshot")

    text = client.get_screen_text()

    # Displayed text

    assert 'HELLO VNC WORLD' in text

    assert 'HELLO VNC' in text

    # Client window title

    assert 'TigerVNC' in text

    # get_screen_text can't get correct string from screenshot

    # assert 'TigerVNC' in text

  '';

}