django-auditlog: Custom signal post_log is triggered even when LogEntry is not created

From https://github.com/jazzband/django-auditlog/blob/master/auditlog/receivers.py#L99

    try:
        changes = model_instance_diff(
            diff_old, diff_new, fields_to_check=fields_to_check
        )

        if force_log or changes:
            LogEntry.objects.log_create(
                instance,
                action=action,
                changes=changes,
                force_log=force_log,
            )
    except BaseException as e:
        error = e
    finally:
        post_log.send(
            sender,
            instance=instance,
            action=action,
            error=error,
            pre_log_results=pre_log_results,
        )
        if error:
            raise error

When changes is None implying that the model was saved with no changes, LogEntry object is not created, but the post_log signal is still being send in the finally block which shouldnt happen.

To reproduce the issue:

1. Set any registered model with a receiver for the post_log signal to print a log
2. Save an object without any changes

I am using the last master commit for this.

Another issue here is that the “Custom Signals” feature is not released yet but is part of the public documentation already - https://django-auditlog.readthedocs.io/en/latest/internals.html#custom-signals