[IPRoute] Filter args not honored since pyroute2>0.8.1

[karelyatin]

In OpenStack neutron we have a periodic job running with pyroute2 master(currently at commit e106ce4) and since the merge of thread-unsafe branch in master the job started to fail https://bugs.launchpad.net/neutron/+bug/2092567

The failure is related to ip route show not honoring filter flags.

Reproducer:-
from pyroute2 import IPRoute
ip = IPRoute()
routes = ip.route('show', table=255)
print("Total routes: %d, Routes List: %s" % (len(routes), [route['table'] for route in routes]))

With master branch it returns:-
Total routes: 20, Routes List: [254, 254, 254, 254, 254, 254, 254, 255, 255, 255, 255, 255, 254, 254, 254, 254, 255, 255, 255, 255]

With 0.8.1 it returns:-
Total routes: 5, Routes List: [255, 255, 255, 255, 255]

Similar applies to other args like family.
from pyroute2 import IPRoute
ip = IPRoute()
routes = ip.route('show', table=255, family=1)
print("Total routes: %d, Routes List: %s" % (len(routes), [route['table'] for route in routes]))

With master it returns:-
Total routes: 20, Routes List: [254, 254, 254, 254, 254, 254, 254, 255, 255, 255, 255, 255, 254, 254, 254, 254, 255, 255, 255, 255]

With 0.8.1 it returns:-
Total routes: 0, Routes List: []

with strict_check it slightly differs.
from pyroute2 import IPRoute
ip = IPRoute(strict_check=True)
routes = ip.route('show',table=255, family=1)
print("Total routes: %d, Routes List: %s" % (len(routes), [route['table'] for route in routes]))

With master branch it returns:-
Total routes: 9, Routes List: [255, 255, 255, 255, 255, 255, 255, 255, 255]

With 0.8.1 it returns:-
Total routes: 0, Routes List: []

[svinota]

Thanks for reporting! Fixing