Find a directory suitable for writing log files. It uses sys.prefix
        to use a path relative to the root. If sys.prefix is /usr, it's the
        system Python, so use /var/log.

def log_root(self):
        """
        Find a directory suitable for writing log files. It uses sys.prefix
        to use a path relative to the root. If sys.prefix is /usr, it's the
        system Python, so use /var/log.
        """
        var_log = (
            os.path.join(sys.prefix, 'var', 'log')
            .replace('/usr/var', '/var')
        )
        if not os.path.isdir(var_log):
            os.makedirs(var_log)
        return var_log