From 5ba5993470a6ad532fc8e842084a574a88876b0a Mon Sep 17 00:00:00 2001
From: Shea Levy <shea@shealevy.com>
Date: Mon, 30 Dec 2013 07:58:14 -0500
Subject: [PATCH] nix-shell --pure: Don't clear IN_NIX_SHELL

Signed-off-by: Shea Levy <shea@shealevy.com>
---
 scripts/nix-build.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/nix-build.in b/scripts/nix-build.in
index fe22058f6..8b66e38a9 100755
--- a/scripts/nix-build.in
+++ b/scripts/nix-build.in
@@ -185,7 +185,7 @@ foreach my $expr (@exprs) {
         # Set the environment.
         if ($pure) {
             foreach my $name (keys %ENV) {
-                next if $name eq "HOME" || $name eq "USER" || $name eq "LOGNAME" || $name eq "DISPLAY" || $name eq "PATH" || $name eq "TERM";
+                next if $name eq "HOME" || $name eq "USER" || $name eq "LOGNAME" || $name eq "DISPLAY" || $name eq "PATH" || $name eq "TERM" || $name eq "IN_NIX_SHELL";
                 delete $ENV{$name};
             }
             # NixOS hack: prevent /etc/bashrc from sourcing /etc/profile.