pin operator assigned wrong type in metadata builder

[lukaszsamson]

    defmodule MyModule do
      def my_fun(a, b) do
        case a do
          ^b -> b
          %{b: ^b} = a -> b
        end
      end
    end

type: {:map, [b: {:local_call, :^, [variable: :b]}], nil}

[Goose97]

We went from this

{:map, [b: {:local_call, :^, [variable: :b]}], nil}

to this

{:map, [b: [variable: :b]], nil}