Return true if some system has a public network.

def hasPublicNet(self, system_name):
        """ Return true if some system has a public network."""

        nets_id = [net.id for net in self.networks if net.isPublic()]
        system = self.get_system_by_name(system_name)
        if system:
            i = 0
            while True:
                f = system.getFeature("net_interface.%d.connection" % i)
                if not f:
                    break
                if f.value in nets_id:
                    return True
                i += 1

        return False