fish: add patch to fix `$PATH` for nix-darwin (#352666)

      hash = "sha256-YUyfVkPNB5nfOROV+mu8NklCe7g5cizjsRTTu8GjslA=";

    };

    patches = [

      # We don’t want to run `/usr/libexec/path_helper` on nix-darwin,

      # as it pulls in paths not tracked in the system configuration

      # and messes up the order of `$PATH`. Upstream are unfortunately

      # unwilling to accept a change for this and have recommended that

      # it should be a distro‐specific patch instead.

      #

      # See:

      #

      # * <https://github.com/LnL7/nix-darwin/issues/122>

      # * <https://github.com/fish-shell/fish-shell/issues/7142>

      ./nix-darwin-path.patch

    ];

    # Fix FHS paths in tests

    postPatch = ''

      # src/fish_tests.cpp

diff --git a/share/config.fish b/share/config.fish

index d85fd1e185..c564e45b27 100644

--- a/share/config.fish

+++ b/share/config.fish

@@ -158,6 +158,7 @@

 #

 if status --is-login

     if command -sq /usr/libexec/path_helper

+        and not set -q __NIX_DARWIN_SET_ENVIRONMENT_DONE

         # Adapt construct_path from the macOS /usr/libexec/path_helper

         # executable for fish; see

         # https://opensource.apple.com/source/shell_cmds/shell_cmds-203/path_helper/path_helper.c.auto.html .