From 373d8b7b38df1f587052675a194b730da1f3703a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Mon, 7 Mar 2016 10:51:46 +0100
Subject: [PATCH] Fix NixOS 15.09 channel generation

---
 mirror-nixos-branch.pl | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mirror-nixos-branch.pl b/mirror-nixos-branch.pl
index 862205c..adf5977 100755
--- a/mirror-nixos-branch.pl
+++ b/mirror-nixos-branch.pl
@@ -50,8 +50,9 @@ my $rev = $evalInfo->{jobsetevalinputs}->{nixpkgs}->{revision} or die;
 print STDERR "release is ‘$releaseName’ (build $releaseId), eval is $evalId, dir is ‘$releaseDir’, Git commit is $rev\n";
 
 # Guard against the channel going back in time.
-my $curRelease = basename(readlink "$channelsDir/$channelName");
-if (defined $curRelease) {
+my $curReleaseDir = readlink "$channelsDir/$channelName";
+if (defined $curReleaseDir) {
+    my $curRelease = basename($curReleaseDir);
     my $d = `nix-instantiate --eval -E "builtins.compareVersions (builtins.parseDrvName \\"$curRelease\\").version (builtins.parseDrvName \\"$releaseName\\").version"`;
     chomp $d;
     die "channel would go back in time from $curRelease to $releaseName, bailing out\n" if $d == 1;