test: issue2551366. Probe for open port in test_liveserver.py Add a method to probe for an open port to wsgi_liveserver.py. Start the roundup server under wsgi on the open port. If a port can't be found, it skips all tests. Also changed all hardcoded URL references to use the dynamicly determined tracker url/port value. I fed my patch to wsgi_liveserver.py upstream at: https://github.com/jerrykan/wsgi-liveserver/issues/3

try:
    from html import escape as html_escape_  # python 3

    def html_escape(string, quote=False):
        # html_escape under python 3 sets quote to true by default
        # make it python 2 compatible
        return html_escape_(string, quote=quote)
except ImportError:
    # python 2 fallback
    from cgi import escape as html_escape  # noqa: F401