From b11cb37044bc145c6d6180cd78a9cadef46f6599 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Mon, 22 Sep 2014 16:53:40 +0200
Subject: [PATCH] Handle derivations without a system attribute

---
 src/c/hydra-eval-jobs.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/c/hydra-eval-jobs.cc b/src/c/hydra-eval-jobs.cc
index d1b7bf63..33e2df3c 100644
--- a/src/c/hydra-eval-jobs.cc
+++ b/src/c/hydra-eval-jobs.cc
@@ -128,6 +128,9 @@ static void findJobsWrapped(EvalState & state, XMLWriter & doc,
 
             DrvInfo::Outputs outputs = drv.queryOutputs();
 
+            if (drv.system == "unknown")
+                throw EvalError("derivation must have a ‘system’ attribute");
+
             xmlAttrs["jobName"] = attrPath;
             xmlAttrs["nixName"] = drv.name;
             xmlAttrs["system"] = drv.system;