Ruby on Rails gem collisions

I am trying to get my Ruby on Rails development environment up and running. I followed the ‘Development shell’ instructions in this repo but I cannot get passed collisions in the nix store.

In my gemset.nix generated by bundix there’s multiple gems which all reference the same source, I believe this is why I am getting the collisions. Example below, but there’s lots of these with the same source!

  actioncable = {
    dependencies = ["actionpack" "activesupport" "nio4r" "websocket-driver" "zeitwerk"];
    groups = ["default" "development"];
    platforms = [];
    source = {
      fetchSubmodules = false;
      rev = "1f6cef4ca546b3a9f7aa12c0f10c7d1d1cfbab5a";
      sha256 = "0fk0a0kq1wcgdnccpxix7r7x2y21awh2ipi808gy7wma5rgayxm9";
      type = "git";
      url = "https://github.com/rails/rails.git";
    };
    version = "7.2.0.alpha";
  };
  actionmailbox = {
    dependencies = ["actionpack" "activejob" "activerecord" "activestorage" "activesupport" "mail"];
    groups = ["default"];
    platforms = [];
    source = {
      fetchSubmodules = false;
      rev = "1f6cef4ca546b3a9f7aa12c0f10c7d1d1cfbab5a";
      sha256 = "0fk0a0kq1wcgdnccpxix7r7x2y21awh2ipi808gy7wma5rgayxm9";
      type = "git";
      url = "https://github.com/rails/rails.git";
    };
    version = "7.2.0.alpha";
  };

My flake.nix looks like this:

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11";
    nixpkgs-ruby.url = "github:bobvanderlinden/nixpkgs-ruby";
    nixpkgs-ruby.inputs.nixpkgs.follows = "nixpkgs";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, nixpkgs-ruby, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};
        ruby = nixpkgs-ruby.lib.packageFromRubyVersionFile {
          file = ./.ruby-version;
          inherit system;
        };

        gems = pkgs.bundlerEnv {
          name = "gemset";
          inherit ruby;
          gemfile = ./Gemfile;
          lockfile = ./Gemfile.lock;
          gemset = ./gemset.nix;
          groups = [ "default" "production" "development" "test" ];
        };
      in
      {
        devShell = with pkgs;
          mkShell {
            buildInputs = [
              gems
              ruby
              bundix
            ];
          };
      });
}

How would I avoid this?