fish: fix regression due to changes in Nixpkgs

Fixes #1701
Fixes #1702

modules/programs/fish.nix

@@ -343,7 +343,12 @@ in {
         # if we haven't sourced the general config, do it
         if not set -q __fish_general_config_sourced
 
-          set -p fish_function_path ${pkgs.fish-foreign-env}/share/fish-foreign-env/functions
+          set --prepend fish_function_path ${
+            if pkgs ? fishPlugins && pkgs.fishPlugins ? foreign-env then
+              "${pkgs.fishPlugins.foreign-env}/share/fish/vendor_functions.d"
+            else
+              "${pkgs.fish-foreign-env}/share/fish-foreign-env/functions"
+          }
           fenv source ${config.home.profileDirectory}/etc/profile.d/hm-session-vars.sh > /dev/null
           set -e fish_function_path[1]