From c222c31745ae7044148c35ca3456ab43137d07e9 Mon Sep 17 00:00:00 2001
From: Aristid Breitkreuz <aristidb@gmail.com>
Date: Mon, 1 Jul 2013 21:04:46 +0200
Subject: [PATCH] do not patch non-existent bash_completion for old kernels

---
 pkgs/os-specific/linux/kernel/perf.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pkgs/os-specific/linux/kernel/perf.nix b/pkgs/os-specific/linux/kernel/perf.nix
index cc5ec7f2f24..83de0effcec 100644
--- a/pkgs/os-specific/linux/kernel/perf.nix
+++ b/pkgs/os-specific/linux/kernel/perf.nix
@@ -12,7 +12,7 @@ stdenv.mkDerivation {
   preConfigure = ''
     cd tools/perf
     sed -i s,/usr/include/elfutils,$elfutils/include/elfutils, Makefile
-    sed -i 's,^have perf,_have perf,' bash_completion
+    -f bash_completion && sed -i 's,^have perf,_have perf,' bash_completion
     export makeFlags="DESTDIR=$out $makeFlags"
   '';