Funky constant lookup change between MRI 1.9.2 vs. 1.9.3

gistfile1.txt

# see this blog post for differences between 1.8.7 vs 1.9.1 vs. 1.9.2: http://jfire.posterous.com/constant-lookup-in-ruby

module M
  X = 100

  def m1
    puts X
  end
end

class C
  extend M

  def self.m2
    puts X
  end
end

def C.m3
  puts X
end

C.m1 # works in 1.9.2 and 1.9.3
C.m3 # works in 1.9.2, generates missing constant exception in 1.9.3
C.m2 # generates missing constant exception in 1.9.2 and 1.9.3