`Cannot find Git revision in ref 'refs/heads/master'` since Nix 2.20

[ShamrockLee]

Description

Starting from Nix 2.20, an error appears when evaluating a Rust derivation built with dream2nix's rust-cargo-lock and buildRustPackage:

       error: Cannot find Git revision 'a1bf3a613f451af7fc0a59411c56abc47fe8e8e1' in ref 'refs/heads/master' of repository 'https://github.com/salsa-rs/salsa.git'! Please make sure that the rev exists on the ref you've specified or add allRefs = true; to fetchGit.

Steps to reproduce

1. Place the flake.nix and flake.lock files in the "Reproduction files" in the same directory and cd.
2. Run nix run github:NixOS/nix/2.19-maintenance flake check path:., and see successful result.
3. Run nix run github:NixOS/nix/2.20-maintenance flake check path:., and see the error:

❯ nix run github:NixOS/nix/2.20-maintenance flake check path:.
error:
       … while checking flake output 'packages'

       … while checking the derivation 'packages.x86_64-linux.ruff'

       … while calling the 'head' builtin
         at /nix/store/g2ysyzdx76m4z7lnmyddcwdz25lx7kn1-source/lib/attrsets.nix:1575:11:
         1574|         || pred here (elemAt values 1) (head values) then
         1575|           head values
             |           ^
         1576|         else

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: Cannot find Git revision 'a1bf3a613f451af7fc0a59411c56abc47fe8e8e1' in ref 'refs/heads/master' of repository 'https://github.com/salsa-rs/salsa.git'! Please make sure that the rev exists on the ref you've specified or add allRefs = true; to fetchGit.

Reproduction files

flake.nix

{
  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
  inputs.flake-parts.url = "github:hercules-ci/flake-parts";
  # Build ruff of custom version with dream2nix
  inputs.dream2nix.url = "github:nix-community/dream2nix";
  # The branch name contains an unfortunate typo.
  inputs.ruff-source.url = "github:astral-sh/ruff/0.5.5";
  inputs.ruff-source.flake = false;

  outputs = {self, ...} @ inputs: let
    inherit (inputs.nixpkgs) lib;
  in
    inputs.flake-parts.lib.mkFlake {inherit inputs;} {
      perSystem = {
        config,
        self',
        inputs',
        pkgs,
        system,
        ...
      }: let
        callDream2NixModule = module:
          inputs.dream2nix.lib.evalModules {
            packageSets.nixpkgs = pkgs;
            modules = [
              module
              {
                paths.projectRoot = ./.;
                paths.projectRootFile = ./flake.nix;
                paths.package = ./.;
              }
            ];
          };
      in {
        packages = {
          ruff = callDream2NixModule (
            {
              config,
              lib,
              dream2nix,
              ...
            }: {
              imports = [
                dream2nix.modules.dream2nix.rust-cargo-lock
                dream2nix.modules.dream2nix.buildRustPackage
              ];

              deps = {nixpkgs, ...}: {
                inherit
                  (nixpkgs)
                  installShellFiles
                  rust-jemalloc-sys
                  ;
                CoreService =
                  if nixpkgs.stdenv.isDarwin
                  then nixpkgs.darwin.apple_sdk.frameworks.CoreService
                  else null;
                # For phases
                ruff-nixpkgs = nixpkgs.ruff;
              };

              name = lib.mkForce "ruff";
              version = lib.mkForce "0.5.5";

              mkDerivation = {
                src = inputs.ruff-source.outPath;
                nativeBuildInputs = with config.deps; [
                  installShellFiles
                ];
                buildInputs = with config.deps; [
                  rust-jemalloc-sys
                  CoreService
                ];
                # Install shell files
                inherit
                  (config.deps.ruff-nixpkgs)
                  postInstall
                  ;
              };

              public = {
                meta = {
                  inherit
                    (config.deps.ruff-nixpkgs.meta)
                    description
                    mainProgram
                    ;
                };
              };
            }
          );
        };
      };
      systems = lib.attrNames inputs.nixpkgs.legacyPackages;
    };
}

flake.lock

{
  "nodes": {
    "dream2nix": {
      "inputs": {
        "nixpkgs": "nixpkgs",
        "purescript-overlay": "purescript-overlay",
        "pyproject-nix": "pyproject-nix"
      },
      "locked": {
        "lastModified": 1722526955,
        "narHash": "sha256-fFS8aDnfK9Qfm2FLnQ8pqWk8FzvFEv5LvTuZTZLREnc=",
        "owner": "nix-community",
        "repo": "dream2nix",
        "rev": "3fd4c14d3683baac8d1f94286ae14fe160888b51",
        "type": "github"
      },
      "original": {
        "owner": "nix-community",
        "repo": "dream2nix",
        "type": "github"
      }
    },
    "flake-parts": {
      "inputs": {
        "nixpkgs-lib": "nixpkgs-lib"
      },
      "locked": {
        "lastModified": 1722555600,
        "narHash": "sha256-XOQkdLafnb/p9ij77byFQjDf5m5QYl9b2REiVClC+x4=",
        "owner": "hercules-ci",
        "repo": "flake-parts",
        "rev": "8471fe90ad337a8074e957b69ca4d0089218391d",
        "type": "github"
      },
      "original": {
        "owner": "hercules-ci",
        "repo": "flake-parts",
        "type": "github"
      }
    },
    "nixpkgs": {
      "locked": {
        "lastModified": 1720181791,
        "narHash": "sha256-i4vJL12/AdyuQuviMMd1Hk2tsGt02hDNhA0Zj1m16N8=",
        "owner": "NixOS",
        "repo": "nixpkgs",
        "rev": "4284c2b73c8bce4b46a6adf23e16d9e2ec8da4bb",
        "type": "github"
      },
      "original": {
        "owner": "NixOS",
        "ref": "nixpkgs-unstable",
        "repo": "nixpkgs",
        "type": "github"
      }
    },
    "nixpkgs-lib": {
      "locked": {
        "lastModified": 1722555339,
        "narHash": "sha256-uFf2QeW7eAHlYXuDktm9c25OxOyCoUOQmh5SZ9amE5Q=",
        "type": "tarball",
        "url": "https://github.com/NixOS/nixpkgs/archive/a5d394176e64ab29c852d03346c1fc9b0b7d33eb.tar.gz"
      },
      "original": {
        "type": "tarball",
        "url": "https://github.com/NixOS/nixpkgs/archive/a5d394176e64ab29c852d03346c1fc9b0b7d33eb.tar.gz"
      }
    },
    "nixpkgs_2": {
      "locked": {
        "lastModified": 1723282977,
        "narHash": "sha256-oTK91aOlA/4IsjNAZGMEBz7Sq1zBS0Ltu4/nIQdYDOg=",
        "owner": "NixOS",
        "repo": "nixpkgs",
        "rev": "a781ff33ae258bbcfd4ed6e673860c3e923bf2cc",
        "type": "github"
      },
      "original": {
        "owner": "NixOS",
        "ref": "nixos-24.05",
        "repo": "nixpkgs",
        "type": "github"
      }
    },
    "purescript-overlay": {
      "inputs": {
        "nixpkgs": [
          "dream2nix",
          "nixpkgs"
        ],
        "slimlock": "slimlock"
      },
      "locked": {
        "lastModified": 1696022621,
        "narHash": "sha256-eMjFmsj2G1E0Q5XiibUNgFjTiSz0GxIeSSzzVdoN730=",
        "owner": "thomashoneyman",
        "repo": "purescript-overlay",
        "rev": "047c7933abd6da8aa239904422e22d190ce55ead",
        "type": "github"
      },
      "original": {
        "owner": "thomashoneyman",
        "repo": "purescript-overlay",
        "type": "github"
      }
    },
    "pyproject-nix": {
      "flake": false,
      "locked": {
        "lastModified": 1702448246,
        "narHash": "sha256-hFg5s/hoJFv7tDpiGvEvXP0UfFvFEDgTdyHIjDVHu1I=",
        "owner": "davhau",
        "repo": "pyproject.nix",
        "rev": "5a06a2697b228c04dd2f35659b4b659ca74f7aeb",
        "type": "github"
      },
      "original": {
        "owner": "davhau",
        "ref": "dream2nix",
        "repo": "pyproject.nix",
        "type": "github"
      }
    },
    "root": {
      "inputs": {
        "dream2nix": "dream2nix",
        "flake-parts": "flake-parts",
        "nixpkgs": "nixpkgs_2",
        "ruff-source": "ruff-source"
      }
    },
    "ruff-source": {
      "flake": false,
      "locked": {
        "lastModified": 1721918821,
        "narHash": "sha256-dqfK6YdAV4cdUYB8bPE9I5FduBJ90RxUA7TMvcVq6Zw=",
        "owner": "astral-sh",
        "repo": "ruff",
        "rev": "fc16d8d04d86aa94a8aac14bbb87089b64d443a1",
        "type": "github"
      },
      "original": {
        "owner": "astral-sh",
        "ref": "0.5.5",
        "repo": "ruff",
        "type": "github"
      }
    },
    "slimlock": {
      "inputs": {
        "nixpkgs": [
          "dream2nix",
          "purescript-overlay",
          "nixpkgs"
        ]
      },
      "locked": {
        "lastModified": 1688610262,
        "narHash": "sha256-Wg0ViDotFWGWqKIQzyYCgayeH8s4U1OZcTiWTQYdAp4=",
        "owner": "thomashoneyman",
        "repo": "slimlock",
        "rev": "b5c6cdcaf636ebbebd0a1f32520929394493f1a6",
        "type": "github"
      },
      "original": {
        "owner": "thomashoneyman",
        "repo": "slimlock",
        "type": "github"
      }
    }
  },
  "root": "root",
  "version": 7
}