From c1323b53e3a1650271469f713804e628509a858c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Mon, 1 Jun 2015 15:08:09 +0200
Subject: [PATCH] Fix fetchurl/fetchTarball

---
 src/libexpr/primops.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 95914626f..355b81adf 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1515,7 +1515,8 @@ void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
     } else
         url = state.forceStringNoCtx(*args[0], pos);
 
-    mkString(v, downloadFileCached(url, unpack), PathSet({url}));
+    Path res = downloadFileCached(url, unpack);
+    mkString(v, res, PathSet({res}));
 }