nixos/plasma6: allow null password for screen lock

[K900]

Description of changes

This was fixed and we missed it, I think?

Fixes #293964, #318782

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[NovaViper]

Can confirm this works!

[rardiol]

Thanks. I'm on 24.05 not unstable but setting security.pam.services.kde.allowNullPassword = true is working for me on both passwordless and passworded accounts with plasmashell 6.0.5. Since this issue negatively affects the graphical installer maybe this should be backported?

[github-actions]

Successfully created backport PR for release-24.05:

• [Backport release-24.05] nixos/plasma6: allow null password for screen lock #321979

[github-actions]

Git push to origin failed for release-24.05 with exitcode 1

[NovaViper]

@rardiol Huh so that confirms it indeed wasn't a KDE issue after all then.

[K900]

It was a KDE issue, but it looks like the fix got backported.