relocking flake when inputs change.

This fixes a 'path dependency' bug, where you'd get into hard-to-reproduce state that wasn't driven by
anysnake2.toml, but by a *series* of anysnake2.tomls.

examples/flake_subdependency/after/.gcroots/github:NixOS_nixpkgs_24.05

@@ -0,0 +1 @@
+/nix/store/wzx1ba5hqqfa23vfrvqmfmkpj25p37mr-source

examples/flake_subdependency/after/.gcroots/github:NixOS_nixpkgs_24.05#dtach

@@ -0,0 +1 @@
+/nix/store/v7qy11nyx968dgw93c6c03l0m7bvi4cl-dtach-0.9

examples/flake_subdependency/after/.gcroots/github:NixOS_nixpkgs_24.05#nixfmt

@@ -0,0 +1 @@
+/nix/store/yw7xxl0kgha3f9gk4yn9sf0k9v45l26q-nixfmt-0.6.0-bin

examples/flake_subdependency/after/.gcroots/github:NixOS_nixpkgs_24.05#singularity

@@ -0,0 +1 @@
+/nix/store/cdvdij4yvz9hj9mhycaz56jfjizxqbg7-singularity-ce-4.1.3

examples/flake_subdependency/after/.gitignore

@@ -0,0 +1,5 @@
+result
+    run_scripts/
+    .*.json
+    .gc_roots
+

examples/flake_subdependency/after/flake.nix

@@ -0,0 +1,73 @@
+{
+  description = "Anysnake2 generated flake";
+  inputs = rec {
+
+    flake-utils = {
+      url =
+        "github:numtide/flake-utils/b1d9ab70662946ef0850d488da1c9019f3a9752a";
+
+    };
+    nixpkgs = {
+      url = "github:NixOS/nixpkgs/24.05";
+
+    };
+    rust-overlay = {
+      url =
+        "github:oxalica/rust-overlay/0be641045af6d8666c11c2c40e45ffc9667839b5";
+      inputs.nixpkgs.follows = "nixpkgs";
+
+    };
+    test = {
+      url =
+        "github:nix-community/poetry2nix/f554d27c1544d9c56e5f1f8e2b8aff399803674e";
+
+    };
+  };
+
+  outputs = { self, flake-utils, nixpkgs, rust-overlay, test }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system overlays;
+          config = { allowUnfree = false; };
+        };
+        R_tracked = null;
+        overlays = [ (import rust-overlay) ];
+        rust = pkgs.rust-bin.stable."1.55.0".minimal.override {
+          extensions = [ "rustfmt" "clippy" ];
+        };
+        _args = with pkgs; {
+          name = "anysnake2_container";
+          #later entries beat earlier entries in terms of /bin symlinks
+          script = ''
+                      ${coreutils}
+                      ${bashInteractive_5}
+                      ${bash}
+            ${cacert}
+            ${fish}
+            ${rust}
+            ${stdenv.cc}
+          '';
+        };
+        helpers = import ./functions.nix { inherit pkgs; };
+      in rec {
+        defaultPackage = (helpers.buildSymlinkImage _args).derivation;
+        oci_image = helpers.buildOCIimage _args;
+        devShell = pkgs.stdenv.mkDerivation {
+          name = "anysnake2-devshell";
+          shellHook = ''
+            export PATH=${defaultPackage}/rootfs/bin:$PATH;
+            if test -f "develop_python_path.bash"; then
+              source "develop_python_path.bash"
+            fi
+          '' + (if R_tracked != null then ''
+            export R_LIBS_SITE=${R_tracked}/lib/R/library/
+          '' else
+            "");
+          nativeBuildInputs = with pkgs;
+            [
+              #%DEVSHELL_INPUTS%
+            ];
+        };
+      });
+}