After adding and removing `load-balancing` configuration there's a PID that exists after the config removing.
This pid used in [[ https://github.com/vyos/vyatta-wanloadbalance/blob/973421035568810e2583187c48d14054970b9806/scripts/dhcp/04-dhcp-wanlb#L3 | dhcp-exit-hook ]]
So if we don't have `load-balancing` in the configuration it tries to send the user signal to not exist process ** kill -s SIGUSR2 xxx**
To reproduce:
```
set load-balancing wan interface-health eth1 nexthop dhcp
commit
delete load-balancing
commit
run renew dhcp interface ethX
```
File
```
vyos@vyos2# file /var/run/vyatta/wlb.pid
/var/run/vyatta/wlb.pid: ASCII text
```
Log:
```
May 04 12:55:14 vyos2 root[8725]: /etc/dhcp/dhclient-exit-hooks.d/04-dhcp-wanlb returned non-zero exit status 1
```
Propose to use **OR** in the hook or remove the PID properly
**kill -s SIGUSR2 $( cat $pid ) 2>/dev/null** => **kill -s SIGUSR2 $( cat $pid ) 2>/dev/null || true**