Doing "su hydra" causes Perl to be invoked with a wrong PERL5LIB (pointing to root's profile), leading to "Can't locate strict.pm".
5QYMALGUFECBH44BDVLFRZR5CQ24UTSEELVMAGDNKY2JAKBZKQ3AC
$machine->mustSucceed("su hydra -c 'NIX_STORE_DIR=/tmp/nix/store NIX_LOG_DIR=/tmp/nix/var/log/nix NIX_STATE_DIR=/tmp/nix/var/nix DBIC_TRACE=1 hydra-server -d' >&2 &");
$machine->mustSucceed("su - hydra -c 'NIX_STORE_DIR=/tmp/nix/store NIX_LOG_DIR=/tmp/nix/var/log/nix NIX_STATE_DIR=/tmp/nix/var/nix NIX_REMOTE= DBIC_TRACE=1 hydra-server -d' >&2 &");
system("NIX_STORE_DIR=/tmp/nix/store NIX_LOG_DIR=/tmp/nix/var/log/nix NIX_STATE_DIR=/tmp/nix/var/nix hydra-evaluator sample default");
system("NIX_STORE_DIR=/tmp/nix/store NIX_LOG_DIR=/tmp/nix/var/log/nix NIX_STATE_DIR=/tmp/nix/var/nix NIX_REMOTE= hydra-evaluator sample default");