From 117b9ecef18e4bf63b84a9cce0b0d3ae7d8910e9 Mon Sep 17 00:00:00 2001
From: Graham Christensen <graham@grahamc.com>
Date: Tue, 3 Mar 2020 22:36:21 -0500
Subject: [PATCH] =?UTF-8?q?Nix.pm:=20readNixFile:=20pass=20=C2=AB--experim?=
 =?UTF-8?q?ental-features=20nix-command=C2=BB?=
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Declarative jobsets were broken by the Nix update, causing
nix cat-file to break silently.

This commit restores declarative jobsets, based on top of a commit
making it easier to see what broke.
---
 src/lib/Hydra/Helper/Nix.pm | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/lib/Hydra/Helper/Nix.pm b/src/lib/Hydra/Helper/Nix.pm
index 8ce284ad..5034c81b 100644
--- a/src/lib/Hydra/Helper/Nix.pm
+++ b/src/lib/Hydra/Helper/Nix.pm
@@ -509,7 +509,8 @@ sub getStoreUri {
 # Read a file from the (possibly remote) nix store
 sub readNixFile {
     my ($path) = @_;
-    return grab(cmd => ["nix", "cat-store", "--store", getStoreUri(), "$path"]);
+    return grab(cmd => ["nix", "--experimental-features", "nix-command",
+                        "cat-store", "--store", getStoreUri(), "$path"]);
 }