Run the following script to verify no panic any more.
```
#!/bin/sh
ifconfig lo0 inet 172.16.0.1/32 alias
jail -c name=parent host.hostname=parent path=/ persist children.max=1 ip4.addr=172.16.0.1
jexec parent /bin/sh -s stdin << EOF
jail -c name=c1 host.hostname=c1 path=/ persist
EOF
# The following will trigger panic
jail -m name=parent ip4.addr=
jexec parent.c1 ifconfig lo0
#jail -R parent
```