From 5626c5cdfb6de664881eb8b79dd54a8f4ca19b8f Mon Sep 17 00:00:00 2001
From: Shea Levy <shea@shealevy.com>
Date: Sat, 12 Jan 2013 09:48:21 -0500
Subject: [PATCH] replace-dependency: don't break nixpkgs for people living in
 the stone age

---
 pkgs/top-level/all-packages.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 325882e66ae0..aead61259053 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -344,9 +344,9 @@ let
     inherit stdenv;
   };
 
-  "replace-dependency" = import ../build-support/replace-dependency.nix {
+  "replace-dependency" = if builtins ? langVersion then import ../build-support/replace-dependency.nix {
     inherit runCommand nix lib;
-  };
+  } else args: throw "You must be using at least nix-1.2 to use replace-dependency";
 
   nukeReferences = callPackage ../build-support/nuke-references/default.nix { };