fish-foreign-env: move to fishPlugins.foreign-env

And relocate the installed fish functions to the `vendor_functions.d` so
that they're automatically loaded.

pkgs/shells/fish/plugins/default.nix

@@ -6,6 +6,8 @@ lib.makeScope newScope (self: with self; {
 
   fishtape = callPackage ./fishtape.nix { };
 
+  foreign-env = callPackage ./foreign-env { };
+
   pure = callPackage ./pure.nix { };
 
 })

pkgs/shells/fish/plugins/foreign-env/default.nix

@@ -0,0 +1,29 @@
+{ lib, buildFishPlugin, fetchFromGitHub, gnused, bash, coreutils }:
+
+buildFishPlugin {
+  pname = "foreign-env";
+  version = "git-20200209";
+
+  src = fetchFromGitHub {
+    owner = "oh-my-fish";
+    repo = "plugin-foreign-env";
+    rev = "dddd9213272a0ab848d474d0cbde12ad034e65bc";
+    sha256 = "00xqlyl3lffc5l0viin1nyp819wf81fncqyz87jx8ljjdhilmgbs";
+  };
+
+  patches = [ ./suppress-harmless-warnings.patch ];
+
+  preInstall = ''
+    sed -e "s|sed|${gnused}/bin/sed|" \
+        -e "s|bash|${bash}/bin/bash|" \
+        -e "s|\| tr|\| ${coreutils}/bin/tr|" \
+        -i functions/*
+  '';
+
+  meta = with lib; {
+    description = "A foreign environment interface for Fish shell";
+    license = licenses.mit;
+    maintainers = with maintainers; [ jgillich ];
+    platforms = with platforms; unix;
+  };
+}

pkgs/shells/fish/plugins/foreign-env/suppress-harmless-warnings.patch

@@ -0,0 +1,23 @@
+diff --git a/functions/fenv.apply.fish b/functions/fenv.apply.fish
+index 34a25e3..3d94135 100644
+--- a/functions/fenv.apply.fish
++++ b/functions/fenv.apply.fish
+@@ -27,11 +27,17 @@ function fenv.apply
+     for variable in $variables
+         set key (echo $variable | sed 's/=.*//')
+         set value (echo $variable | sed 's/[^=]*=//')
++        set ignore PATH _
+ 
+         if test "$key" = 'PATH'
+           set value (echo $value | tr ':' '\n')
+         end
+ 
+-        set -g -x $key $value
++        if contains $key $ignore
++          set -g -x $key $value 2>/dev/null
++        else
++          set -g -x $key $value
++        end
++
+     end
+ end