Created attachment 1160546 [details]
Logs

Description of problem:
Management network's gateway wiped out after detaching a network with gateway(different subnet then the ovirtmgmt) from host. 

When attaching network to host with static ip and gateway(not in the same subnet as the management network), the host will get the new gateway instead the management's one, example:
- Before attaching the other network to host -->
[root@pink-vds2 ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.35.128.254   0.0.0.0         UG    0      0        0 ovirtmgmt
10.35.128.0     0.0.0.0         255.255.255.0   U     0      0        0 ovirtmgmt
169.254.0.0     0.0.0.0         255.255.0.0     U     1008   0        0 ovirtmgmt
 
- After attaching the other network to host -->
[root@pink-vds2 ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         6.6.6.254       0.0.0.0         UG    0      0        0 n2
6.6.6.0         0.0.0.0         255.255.255.0   U     0      0        0 n2
10.35.128.0     0.0.0.0         255.255.255.0   U     0      0        0 ovirtmgmt
169.254.0.0     0.0.0.0         255.255.0.0     U     1008   0        0 ovirtmgmt
169.254.0.0     0.0.0.0         255.255.0.0     U     1010   0        0 n2

- After detaching the other network from the host, there will be no gateway and host will go to non-responsive state.

Version-Release number of selected component (if applicable):
4.0.0-0.7.master.el7ev

How reproducible:
100

Steps to Reproduce:
1. Running host on 4.0 with management network
2. Attach other network, 'net1' to second interface on the host via setup networks with static ip - 6.6.6.6, prefix - 24 and gateway 6.6.6.254 and approve operation
3. Detach the network

Actual results:
No gateway on the host. Host moves to non-responsive state. 

Expected results:
Ovirtmgmt's gateway should remain.