set fish as default login shell via workaround

hosts/server/configuration.nix

@@ -34,7 +34,6 @@
       ];
       home = "/home/srv";
       isNormalUser = true;
-      shell = pkgs.fish;
     };
   };
 

modules/home-manager/features/fish.nix

@@ -1,4 +1,9 @@
-{ config, lib, ... }:
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
 let
   feature = "fish";
 in
@@ -22,6 +27,18 @@ in
         vim = "nvim";
       };
     };
+
+    # https://nixos.wiki/wiki/Fish#Setting_fish_as_your_shell
+    programs.bash = {
+      enable = true;
+      initExtra = ''
+        if [[ $(${pkgs.procps}/bin/ps --no-header --pid=$PPID --format=comm) != "fish" && -z ''${BASH_EXECUTION_STRING} ]]
+        then
+          shopt -q login_shell && LOGIN_OPTION='--login' || LOGIN_OPTION=""
+          exec ${pkgs.fish}/bin/fish $LOGIN_OPTION
+        fi
+      '';
+    };
   };
 
   imports = [ ];