I had this random failure (one in 3 builds) - can we mark this tests as broken on ovirt ci
until we make it more reliable?

00:04:16.904 ======================================================================
00:04:16.905 ERROR: test_add_ipv6_gateway_given_existing_ipv4_and_ipv6_gateways (network.ip_address_test.TestAddressSetup)
00:04:16.906 ----------------------------------------------------------------------
00:04:16.906 Traceback (most recent call last):
00:04:16.906   File "/home/jenkins/workspace/vdsm_master_check-patch-el7-x86_64/vdsm/tests/network/ip_address_test.py", line 147, in test_add_ipv6_gateway_given_existing_ipv4_and_ipv6_gateways
00:04:16.908     address.add(nic, ipv4=None, ipv6=ipv6)
00:04:16.908   File "/home/jenkins/workspace/vdsm_master_check-patch-el7-x86_64/vdsm/lib/vdsm/network/ip/address/__init__.py", line 277, in add
00:04:16.909     _add_ipv6_address(iface, ipv6)
00:04:16.909   File "/home/jenkins/workspace/vdsm_master_check-patch-el7-x86_64/vdsm/lib/vdsm/network/ip/address/__init__.py", line 292, in _add_ipv6_address
00:04:16.910     ipwrapper.addrAdd(iface, ipv6addr, ipv6netmask, family=6)
00:04:16.911   File "/home/jenkins/workspace/vdsm_master_check-patch-el7-x86_64/vdsm/lib/vdsm/network/ipwrapper.py", line 561, in addrAdd
00:04:16.911     _exec_cmd(command)
00:04:16.912   File "/home/jenkins/workspace/vdsm_master_check-patch-el7-x86_64/vdsm/lib/vdsm/network/ipwrapper.py", line 482, in _exec_cmd
00:04:16.912     raise exc(returnCode, error.splitlines())
00:04:16.913 IPRoute2Error: (2, ['RTNETLINK answers: File exists'])
00:04:16.913 -------------------- >> begin captured logging << --------------------
00:04:16.914 2018-02-26 12:31:00,244 DEBUG (MainThread) [root] /sbin/ip link add name dummy_aZGko type dummy (cwd None) (cmdutils:150)
00:04:16.915 2018-02-26 12:31:00,256 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:16.915 2018-02-26 12:31:00,260 DEBUG (netlink/events) [root] START thread <Thread(netlink/events, started daemon 140705544533760)> (func=<bound method Monitor._scan of <vdsm.network.netlink.monitor.Monitor object at 0x5c51150>>, args=(), kwargs={}) (concurrent:192)
00:04:16.917 2018-02-26 12:31:00,261 DEBUG (MainThread) [root] /sbin/ip link set dev dummy_aZGko up (cwd None) (cmdutils:150)
00:04:16.918 2018-02-26 12:31:00,272 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:16.919 2018-02-26 12:31:00,275 DEBUG (netlink/events) [root] FINISH thread <Thread(netlink/events, started daemon 140705544533760)> (concurrent:195)
00:04:16.920 2018-02-26 12:31:00,279 DEBUG (MainThread) [root] /sbin/ip route show to 0.0.0.0/0 table main (cwd None) (cmdutils:150)
00:04:16.921 2018-02-26 12:31:00,293 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:16.921 2018-02-26 12:31:00,295 DEBUG (MainThread) [root] /sbin/ip -6 route show to ::/0 table main (cwd None) (cmdutils:150)
00:04:16.922 2018-02-26 12:31:00,311 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:16.923 2018-02-26 12:31:00,313 DEBUG (MainThread) [root] /sbin/ip -4 addr add dev dummy_aZGko 192.168.99.1/255.255.255.248 (cwd None) (cmdutils:150)
00:04:16.924 2018-02-26 12:31:00,328 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:16.925 2018-02-26 12:31:00,329 DEBUG (MainThread) [root] /sbin/ip -4 route add default via 192.168.99.6 (cwd None) (cmdutils:150)
00:04:16.925 2018-02-26 12:31:00,340 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:16.926 2018-02-26 12:31:00,342 DEBUG (MainThread) [root] /sbin/ip -6 addr flush dev dummy_aZGko scope global (cwd None) (cmdutils:150)
00:04:16.927 2018-02-26 12:31:00,363 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:16.928 2018-02-26 12:31:00,364 DEBUG (MainThread) [root] /sbin/ip -6 addr add dev dummy_aZGko 2001:99::1/64 (cwd None) (cmdutils:150)
00:04:16.929 2018-02-26 12:31:00,398 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:16.929 2018-02-26 12:31:00,399 DEBUG (MainThread) [root] /sbin/ip -6 route add default via 2001:99::99 dev dummy_aZGko (cwd None) (cmdutils:150)
00:04:16.930 2018-02-26 12:31:00,410 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:16.931 2018-02-26 12:31:00,412 DEBUG (MainThread) [root] /sbin/ip -6 addr flush dev dummy_aZGko scope global (cwd None) (cmdutils:150)
00:04:16.932 2018-02-26 12:31:00,441 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:16.932 2018-02-26 12:31:00,442 DEBUG (MainThread) [root] /sbin/ip -6 addr add dev dummy_aZGko 2001:99::1/64 (cwd None) (cmdutils:150)
00:04:17.049 2018-02-26 12:31:00,473 DCoverage.py warning: Module /home/jenkins/workspace/vdsm_master_check-patch-el7-x86_64/vdsm/vdsm was never imported. (module-not-imported)
00:04:32.618 EBUG (MainThread) [root] FAILED: <err> = 'RTNETLINK answers: File exists\n'; <rc> = 2 (cmdutils:158)
00:04:32.619 2018-02-26 12:31:00,482 DEBUG (MainThread) [root] /sbin/ip link del dev dummy_aZGko (cwd None) (cmdutils:150)
00:04:32.619 2018-02-26 12:31:00,549 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (cmdutils:158)
00:04:32.620 --------------------- >> end captured logging << ---------------------