vr: fix python exception when configure VRs (#4489)
vr: fix python exception when configure VRs (#4489)

before
```
root@r-27-VM:/var/cache/cloud# /opt/cloud/bin/configure.py monitor_service.json
ERROR:root:Command 'ip link show eth0 | grep 'state DOWN'' returned non-zero exit status 1
```

with this change
```
root@r-27-VM:/var/cache/cloud# /opt/cloud/bin/configure.py monitor_service.json
root@r-27-VM:/var/cache/cloud#
```
GabrielBrascher/cloudstack,GabrielBrascher/cloudstack,GabrielBrascher/cloudstack,GabrielBrascher/cloudstack,GabrielBrascher/cloudstack,GabrielBrascher/cloudstack,GabrielBrascher/cloudstack