From 5c5223d46b5d159e6c297feeb0ee277536e9e158 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 7 Dec 2017 15:57:06 +0100
Subject: [PATCH] make-tarball.nix: Fix <nixpkgs> check

This was broken by 6bcf1944494973029071411bb378d4262ce2a678, which
caused the result of the check to be ignored (since xargs will return
a non-zero exit status if *any* grep doesn't find a match).
---
 pkgs/top-level/make-tarball.nix | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/pkgs/top-level/make-tarball.nix b/pkgs/top-level/make-tarball.nix
index 16940761e6dc..ccd7b89fc12d 100644
--- a/pkgs/top-level/make-tarball.nix
+++ b/pkgs/top-level/make-tarball.nix
@@ -43,8 +43,10 @@ releaseTools.sourceTarball rec {
     echo 'abort "Illegal use of <nixpkgs> in Nixpkgs."' > $TMPDIR/barf.nix
 
     # Make sure that Nixpkgs does not use <nixpkgs>
-    if (find pkgs -type f -name '*.nix' -print | xargs grep '<nixpkgs\/'); then
+    badFiles=$(find pkgs -type f -name '*.nix' -print | xargs grep -l '^[^#]*<nixpkgs\/' || true)
+    if [[ -n $badFiles ]]; then
         echo "Nixpkgs is not allowed to use <nixpkgs> to refer to itself."
+        echo "The offending files: $badFiles"
         exit 1
     fi