Fix PTR.bind_render_record
Fix PTR.bind_render_record

If reverse_domain didn't include all four octets, the rendered record
would be wrong.

OSU-Net/cyder,drkitty/cyder,OSU-Net/cyder,murrown/cyder,drkitty/cyder,OSU-Net/cyder,akeym/cyder,murrown/cyder,akeym/cyder,murrown/cyder,drkitty/cyder,akeym/cyder,zeeman/cyder,drkitty/cyder,zeeman/cyder,OSU-Net/cyder,zeeman/cyder,zeeman/cyder,akeym/cyder,murrown/cyder