Enables IPv6 forwarding

[mchf]

bnc#916013

[jreidinger]

this is not necessary as you write it with second call.

[mvidner]

I think this is VERY confusing. How should I know which of these to use?

SCR.Read(path(SYSCTL_IPV6_PATH))
SCR.Read(path("#{SYSCTL_AGENT_PATH}.#{SYSCTL_IPV6_PATH}"))
SCR.Read(path("#{SYSCTL_AGENT_PATH}.\"#{SYSCTL_IPV6_PATH}\""))

Thinking of it, the best seems

SYSCTL_AGENT_PATH = path(".etc.sysctl_conf")
SYSCTL_IPV4_PATH = SYSCTL_AGENT_PATH + "net.ipv4.ip_forward"  # add as a single path component
SYSCTL_IPV6_PATH = SYSCTL_AGENT_PATH + "net.ipv6.conf.all.forwarding"
...
SCR.Read(SYSCTL_IPV6_PATH)

(There is a difference between path(".foo") + ".bar.baz" and path(".foo") + path(".bar.baz") which I will need to document properly, Yast.Path#+ does not mention it)

[mvidner]

Oh, I see, SYSCTL_IPV9_PATH are used as an argument to sysctl -w. Then I'd use

# sysctl keys, used as *single* SCR path components below
IPV4_SYSCTL = "net.ipv4.ip_forward"
IPV6_SYSCTL = "net.ipv6.conf.all.forwarding"
# SCR paths
SYSCTL_AGENT_PATH = path(".etc.sysctl_conf")
SYSCTL_IPV4_PATH = SYSCTL_AGENT_PATH + IPV4_SYSCTL
SYSCTL_IPV6_PATH = SYSCTL_AGENT_PATH + IPV6_SYSCTL

[mvidner]

LGTM, thank you!

[mchf]

rebased, merging once travis is done. Thanks for reviews.