super inside initialize

[petoem]

In #4762 @RX14 said its possible to use super from the child constructor.
Using the same example code as in the other issue, but adding a constructor that only calls super doesn't work.
https://play.crystal-lang.org/#/r/2gb3

class Parent
  property a : Int32

  def initialize(@a)
  end

  def initialize
    @a = 1
  end
end

class Child < Parent
  def initialize
    super
  end
  def initialize(a)
    @a = a
  end
end

puts Child.new.a

Outputs:

Error in line 13: this 'initialize' doesn't initialize instance variable '@a' of Parent, with Child < Parent, rendering it nilable

But the fun part starts now. If I remove the second constructor from the class Child it magically works.
https://play.crystal-lang.org/#/r/2gb4

class Parent
  property a : Int32

  def initialize(@a)
  end

  def initialize
    @a = 1
  end
end

class Child < Parent
  def initialize
    super
  end
end

puts Child.new.a

Now crystal detects that the Child classes initialize method calls super which calls Parent classes initialize method that initializes instance variable @a of Parent.

[faustinoaq]

If you use super(a) instead of initialize(@a) the code works:

class Parent
  property a : Int32

  def initialize(@a)
  end

  def initialize
    @a = 1
  end
end

class Child < Parent
  def initialize
    super
  end
  def initialize(a)
    super(a)
  end
end

puts Child.new.a # => 1

Minimal code with this issue:

class A
  def initialize(@a = 1)
  end
end

class B < A
  def initialize
    super
  end
  def initialize(@a)
  end
end

B.new

Outputs:

Error in line 7: this 'initialize' doesn't initialize instance variable '@a' of A, with B < A, rendering it nilable

[RX14]

This looks like a genuine bug to me. super calls should count for variable initialization, and i can't see a way which this could be abused to break initialization.