bool retry = true;

    StepResult res = sRetry;

        retry = doBuildStep(destStore, step, reservation->machine);

        res = doBuildStep(destStore, step, reservation->machine);

    if (retry) {
        {

    if (res != sDone) {
        if (res == sRetry) {

bool State::doBuildStep(nix::ref<Store> destStore, Step::ptr step,

State::StepResult State::doBuildStep(nix::ref<Store> destStore, Step::ptr step,

            return true;

            return sMaybeCancelled;

            return true;

            return sRetry;

    return false;

    return sDone;

    bool doBuildStep(nix::ref<nix::Store> destStore, Step::ptr step,
        Machine::ptr machine);

    enum StepResult { sDone, sRetry, sMaybeCancelled };
    StepResult doBuildStep(nix::ref<nix::Store> destStore,
        Step::ptr step, Machine::ptr machine);