'Overwrite L3Scheduler\'s method to filter by availability zone.'

def _get_routers_can_schedule(self, plugin, context, routers, l3_agent):

    target_routers = []
    for r in routers:
        az_hints = self._get_az_hints(r)
        if ((not az_hints) or (l3_agent['availability_zone'] in az_hints)):
            target_routers.append(r)
    if (not target_routers):
        return []
    return super(AZLeastRoutersScheduler, self)._get_routers_can_schedule(plugin, context, target_routers, l3_agent)
