Test for breaking ties in paging is wrong (?)

In registry/db/api.py we have this code:

       if sort_dir == 'desc':
            query = query.filter(
                or_(sort_key_attr < marker_value,
                    and_(sort_key_attr == marker_value,
                         models.Image.created_at < marker_image.created_at,
                         models.Image.id < marker)))
        else:
            query = query.filter(
                or_(sort_key_attr > marker_value,
                    and_(sort_key_attr == marker_value,
                         models.Image.created_at > marker_image.created_at,
                         models.Image.id > marker)))

I think there's a few problems here:

Normally the sort_key_attr is created_at. So the second test will never match, because created_at cannot be < X and == X.

I think this should be:
                      models.Image.created_at <= marker_image.created_at,

Further, I think the second test should also be <=, not >, because I think this is supposed to be checking for chronological order (i.e. we don't get 'new' results injected into a previous search) ?

This is related to, but different from Bug #930543. Using the same hack to force the timestamps the same shows up the problems here.