def wrap(m)
  Module.new{
    include m
    def foo
      super * 3
    end
  }
end

module A
  def foo
    "Hello!"
  end
end

# stack level too deep (SystemStackError)  in 1.9
$mod = [A,A]
$mod.map{|mod| wrap(mod) }.each{|m|
  p Class.new{ include m }.new.foo
}
# NO error in 1.9 when removing the map
$mod.each{|mod| 
  m = wrap(mod)
  p Class.new{ include m }.new.foo
}

# Also an error on 'manual map'
$mod = [wrap(A),wrap(A)]
$mod.each{|m|
  p Class.new{ include m }.new.foo
}

# But no error on mapping single-element arrays
$mod = [A]
$mod.map{|mod| wrap(mod) }.each{|m|
  p Class.new{ include m }.new.foo
}