From 668fef2e4f1c7758e2a55e355b4826014d5b7ba9 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 24 Feb 2017 13:31:46 +0100
Subject: [PATCH] nix-shell: Overwrite environment variables

Need to remember that std::map::insert() and emplace() don't overwrite
existing entries...

This fixes a regression relative to 1.11 that in particular triggers
in nested nix-shells.

Before:

  $ nativeBuildInputs=/foo nix-shell -p hello --run 'hello'
  build input /foo does not exist

After:

  $ nativeBuildInputs=/foo nix-shell -p hello --run 'hello'
  Hello, world!
---
 src/nix-build/nix-build.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index ee030c57b..f4484ba57 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -408,7 +408,7 @@ int main(int argc, char ** argv)
                 env["NIX_STORE"] = store->storeDir;
 
                 for (auto & var : drv.env)
-                    env.emplace(var);
+                    env[var.first] = var.second;
 
                 restoreAffinity();