From f696af0fab1d610aa8db767e2c7e610e6b7f0899 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Tue, 22 Dec 2015 17:05:29 +0100
Subject: [PATCH] Fix bad error message in Darwin chroots

---
 src/libstore/build.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index e522cb8b4..418956feb 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -2505,7 +2505,9 @@ void DerivationGoal::runChild()
             sandboxProfile += "(allow file-read* file-write* process-exec\n";
             for (auto & i : dirsInChroot) {
                 if (i.first != i.second)
-                    throw SysError(format("can't map '%1%' to '%2%': mismatched impure paths not supported on darwin"));
+                    throw Error(format(
+                        "can't map '%1%' to '%2%': mismatched impure paths not supported on Darwin")
+                        % i.first % i.second);
 
                 string path = i.first;
                 struct stat st;