fix setting myip in FAI_CONFIG_SCR in /var/log/fai/variables

[KarolNi]

Hello
I'm trying to make fai-server in vagrant (https://github.com/KarolNi/fai_server_vagrant) and had issue with multiple network interfaces (vagrant creates one for internal stuff).
This change fixed it (when $SERVERINTERFACE is set). As far as I could find out $dev was never set.
I think this is the only place affected, but you may look here: d26ee40
Also I don't know whether I should write some changelog records

[Mrfai]

Thanks for reporting this bug. You are right $dev is never set. I've modified your fix and use bash variable substitution instead of a pipe.

• myip=$(ip ad show $dev|sed -ne '/127.0.0.1/!{s/^[ \t]inet[ \t]([0-9.]+)/.*$/\1/p}'|head -1)

• myip=${iprange%/*}