Fix minor issue with `Kernel#is_a?` specs added recently
Fix minor issue with `Kernel#is_a?` specs added recently

ruby/rubyspec,ruby/spec,nobu/rubyspec,eregon/rubyspec,ruby/rubyspec,ruby/spec,nobu/rubyspec,nobu/rubyspec,eregon/rubyspec,ruby/spec,eregon/rubyspec