yielding to a block within class_eval does not set self in the block?

class-eval-yield.rb

class A
  def self.my_eval
    B.class_eval do
      puts "self in A.my_eval: #{self}"
      yield
    end
  end
end

class B
  A.my_eval do
    puts "self in B: #{self}"
  end
end

A.my_eval do
  puts "self in top level block: #{self}"
end

# this will output:
# self in A.my_eval: B
# self in B: B
# self in A.my_eval: B
# self in top level block: main

# 2 and 4 are really strange.. I would have guessed self would be forwarded within the block.
# binding?