Comment 1 for bug 1471637

A regular L2+L3 network with 0.0.0.0/8 subnet seems to work without
any issues. The network was created successfully and VMs with ports
in the network were spawned and assigned IP addresses. This indicates
we shouldn't have any problem using this subnet for L2 only networks.

We should ideally disallow 0.0.0.0/8 for L3 only and L2+L3 networks
since the subnet is reserved and addresses in the subnet cannot be
used as destination addresses.