Comment 4 for bug 1728948

I tried to add "respawn_timeout" to dhclient process and it looks that this helps for this issue.
For example in http://logs.openstack.org/78/545778/1/check/neutron-fullstack/050ba41/logs/dsvm-fullstack-logs/TestUninterruptedConnectivityOnL2AgentRestart.test_l2_agent_restart_LB,Flat-network_.txt.gz#_2018-02-19_09_59_44_177 - dhclient is stopped due to error, then it is restarted 10 seconds later and test is passed