Weird behavior of defined?(super) check

Lately I came across some weird behavior with the `defined?` operator used to check if `super` keyword can be used in current context. Usually it works fine, but when I tried to combine the `defined? super` check with a tiny bit of metaprogramming, it gave me unexpected results. It's easier to show then to describe, so here is a distilled example to illustrate the problem: ``` class A; def self.def_f!; singleton_class.send(:define_method, :f) { defined? super } end end class AA < A; end ``` (`A` and `AA` classes both have `.def_f!` class method) ``` A.def_f! A.f # => nil AA.f # => nil ``` (`A.f` has no super and `AA.f` dispatches to `A.f`, so everything's OK so far, but...) ``` AA.def_f! # define its own .f method in the AA class AA.f # => "super" A.f # => "super" # WHY??? ``` Could anyone explain me the last line? `A.f` has no super method, then why it returns `"super"` instead of `nil`? Is it a bug? (I tried it in 1.9.2 and 1.9.3—same results) UPD: I opened a ticket on the Ruby bugtracker: http://bugs.ruby-lang.org/issues/6644