bud rebuild errors with: unrecognised flag '--extra-experimental-features'

[stites]

On a clean build of devos+bud that I provisioned last week I get the following:

❯ bud rebuild HOST boot
error: unrecognised flag '--extra-experimental-features'

bud is currently pinned to the main branch:

❯ \grep -A 20 bud flake.lock
    "bud": {
      "inputs": {
        "beautysh": "beautysh",
        "devshell": [
          "digga",
          "devshell"
        ],
        "nixpkgs": [
          "nixos"
        ]
      },
      "locked": {
        "lastModified": 1633877936,
        "narHash": "sha256-+o3n6s7fR8dBGRldTGelyp2j3jSyTlrniOXwNfmMG20=",
        "owner": "divnix",
        "repo": "bud",
        "rev": "15df091133ff95216c321b09be04905c0a0944c4",
        "type": "github"
      },
      "original": {
        "owner": "divnix",
        "repo": "bud",
        "type": "github"
      }
    },

the version of nix provided in the devos shell (via direnv) is pretty new. Maybe this is the problem (also note the warnings)?

❯ nix --version
warning: unknown experimental feature 'ca-references'
warning: unknown experimental feature 'ca-references'
nix (Nix) 2.5pre20211126_55275fc

I am currently working around this by running nixos-rebuild --flake directly, but this subcommand is currently unusable on my box.