server: Fix Subnet.update_info() method.
server: Fix Subnet.update_info() method.

If update_info() is called directly on the object instead of while being
constructed, the update_info() method doesn't succeed because it's
trying to fetch information about an IP address instead of a subnet.

Signed-off-by: aszlig <ee1aa092358634f9c53f01b5a783726c9e21b35a@redmoonstudios.org>

RedMoonStudios/hetzner