From 9334b84d6fd04a2299b9e4bb2ef4f020cd614f39 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Wed, 13 Aug 2014 16:29:00 +0200
Subject: [PATCH] Fix registerRoot

Fixes #175.
---
 src/lib/Hydra/Helper/Nix.pm | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/lib/Hydra/Helper/Nix.pm b/src/lib/Hydra/Helper/Nix.pm
index 9705fb9d..57db29c8 100644
--- a/src/lib/Hydra/Helper/Nix.pm
+++ b/src/lib/Hydra/Helper/Nix.pm
@@ -79,6 +79,7 @@ sub gcRootFor {
 sub registerRoot {
     my ($path) = @_;
     my $link = gcRootFor $path;
+    return if -e $link;
     open ROOT, ">$link" or die "cannot create GC root `$link' to `$path'";
     close ROOT;
 }