I've been doing some unit tests with ruby -W.  Wow did I have a lot to
clean up but I still can't get past one warning.  I've boiled it down
to this example:

o = Object.new
def o.foo
   'foo'
end
class << o
   undef_method :foo
end
def o.foo
   'foo'
end

# undef_method_test.rb:8: warning: redefine foo

Is my head broken or ruby -W broken?  I'm thinking the former.

TIA,
_ugly