Description of problem:
firewalld fails to assign a custom zone to an interface.

Version-Release number of selected component (if applicable):
firewalld-0.2.12-2.fc18.noarch

How reproducible:
Every time

Steps to Reproduce:
1. Create this openvpn zone (I created it from the GUI):
<?xml version="1.0" encoding="utf-8"?>
<zone target="DROP">
  <short>OpenVPN</short>
  <description>OpenVPN server</description>
  <icmp-block name="redirect"/>
  <icmp-block name="router-solicitation"/>
  <icmp-block name="parameter-problem"/>
  <icmp-block name="router-advertisement"/>
</zone>
2. Assign the zone to the tun-openvpn interface:
firewall-cmd --zone=openvpn --add-interface=tun-openvpn
  
Actual results:
Error: COMMAND_FAILED: '/sbin/iptables -N DROP -t filter' failed: iptables v1.4.16.2: chain name may not clash with target name

Try `iptables -h' or 'iptables --help' for more information.


Expected results:
No errors

Additional info:
firewall-config-0.2.12-2.fc18.noarch
iptables-1.4.16.2-5.fc18.i686
kernel-PAE-3.7.9-201.fc18.i686