Merge pull request #1417 from Mindavi/bugfix/s3backup

S3Backup: fix compilation issue for undef MACHINE_LOCAL_STORE var

src/lib/Hydra/Plugin/S3Backup.pm

@@ -14,6 +14,7 @@ use Nix::Config;
 use Nix::Store;
 use Hydra::Model::DB;
 use Hydra::Helper::CatalystUtils;
+use Hydra::Helper::Nix;
 
 sub isEnabled {
     my ($self) = @_;