adding more resiliancy to the ifup-public script. we want it to maybe fail if it doesn't know what to do with the variable. not just silently continue

files/qemu-ifup-public

@@ -62,7 +62,11 @@ for IP in "${IPS[@]}"; do
         echo "we got IPv6 with prefix ${BASH_REMATCH[0]}"
         ip route add ${IP} dev ${IFACE} via $(eui64 $PUBLICMAC)
 
-     else										### don't know what we have but something we can't work with
+     elif [[ $IP =~ ^\ *$ ]]; then
+        echo "we just got an empty string. so not gonna do anything. probably due to splitting the comma"
+
+     else
         echo "Unable to detect with what prefix I'm working with"
+        exit 10
    fi
 done