    # File lib/chef/provider/group/pw.rb, line 64
            def set_members_option
              opt = ""
              unless @new_resource.members.empty?
                opt << " -M #{@new_resource.members.join(',')}"
                Chef::Log.debug("#{@new_resource} setting group members to #{@new_resource.members.join(', ')}")
              else
                # New member list is empty so we should delete any old group members
                unless @current_resource.members.empty?
                  opt << " -d #{@current_resource.members.join(',')}"
                  Chef::Log.debug("#{@new_resource} removing group members #{@current_resource.members.join(', ')}")
                else
                  Chef::Log.debug("#{@new_resource} not changing group members, the group has no members")
                end
              end
              opt
            end