Created attachment 1297443 [details]
vdsm, supervdsm and engine logs

Description of problem:
When trying to hotplug vNIC with no network (empty) to running VM the operation fails with error:

jsonrpc.Executor/0::DEBUG::2017-07-13 10:28:53,448::utils::689::root::(execCmd) FAILED: <err> = 'Network ;vdsmdummy; does not exist\nTraceback (most recent call last):\n  File "/usr/libexec/vdsm/hooks/before_nic_hotplug/50_ovs", line 130, in <module>\n    main()\n  File "/usr/libexec/vdsm/hooks/before_nic_hotplug/50_ovs", line 54, in main\n    ovs_device(domxml)\n  File "/usr/libexec/vdsm/hooks/before_nic_hotplug/50_ovs", line 42, in ovs_device\n    hooking.exit_hook(\'Network %s does not exist\' % source_bridge)\n  File "/usr/share/vdsm/hooking.py", line 84, in exit_hook\n    sys.exit(return_code)\nSystemExit: 2\n\n'; <rc> = 2
jsonrpc.Executor/0::INFO::2017-07-13 10:28:53,449::hooks::107::root::(_runHooksDir) Network ;vdsmdummy; does not exist
Traceback (most recent call last):
  File "/usr/libexec/vdsm/hooks/before_nic_hotplug/50_ovs", line 130, in <module>
    main()
  File "/usr/libexec/vdsm/hooks/before_nic_hotplug/50_ovs", line 54, in main
    ovs_device(domxml)
  File "/usr/libexec/vdsm/hooks/before_nic_hotplug/50_ovs", line 42, in ovs_device
    hooking.exit_hook('Network %s does not exist' % source_bridge)
  File "/usr/share/vdsm/hooking.py", line 84, in exit_hook
    sys.exit(return_code)
SystemExit: 2
 

Version-Release number of selected component (if applicable):
vdsm-4.17.42-1.el7ev.noarch

How reproducible:
100%

Steps to Reproduce:
1. Start VM
2. Add vNIC with empty network to the VM