puppetlabs/puppetlabs-firewall — pull request #104 by wuwx (2013-01-25 18:11:00+00:00)
Title: ip6tables provider allways execute /sbin/iptables command

OS: CentOS 6.3
Puppet: 3.0.2
Ruby: 1.8.7

I think because optional_commands check iptables method has definded at iptables prodider, so ip6tables provider not define iptables method again.