Fixed restore from checkpoint (was always failing)

[quadrifoglio]

if (!c->is_defined(c)) {
    fprintf(stderr, "%s is not defined\n", my_args.name);
    lxc_container_put(c);
    exit(1);
}

Based on this code from the lxc-checkpoint command, I think the container should be defined in order to process a restore from a checkpoint.

[caglar10ur]

LGTM, @tych0 any objections changing this behavior?

[tych0]

Sorry about the delay, I was on vacation. I think actually we can just drop the defined check entirely from go-lxc. In LXD, we don't "define" containers in the liblxc sense, since their config files never exist on disk, but only in memory. So we can't merge this as is, because it will break LXD's migration.

The check in lxc-checkpoint is basically just to print a user friendly error message, since lxc-checkpoint relies on the container being configured on disk, as that's where it tries to load the config from.

However, at the API level, there's nothing that requires a container to be "defined" in the liblxc sense, so we can just drop the check, I think.

[caglar10ur]

[I remember replying this but the comment is gone, so trying again]

@quadrifoglio do you want to drop refresh this PR and drop the isDefined part?

[quadrifoglio]

Done, I removed the isDefined check.

[tych0]

LGTM

[caglar10ur]

Thanks!