paginate_query explodes when sort_keys contains a boolean column

The paginate_query function explodes if a marker is passed in and one of the sort_keys is a boolean column.

      File "neutron/db/db_base_plugin_v2.py", line 1333, in get_ports
        page_reverse=page_reverse)
      File "neutron/db/db_base_plugin_v2.py", line 1322, in _get_ports_query
        sort_dirs=sort_dirs)
      File "/opt/stack/neutron/.tox/py27/local/lib/python2.7/site-packages/oslo_db/sqlalchemy/utils.py", line 235, in paginate_query
        crit_attrs.append((model_attr > marker_values[i]))
      File "/opt/stack/neutron/.tox/py27/local/lib/python2.7/site-packages/sqlalchemy/sql/operators.py", line 318, in __gt__
        return self.operate(gt, other)
      File "/opt/stack/neutron/.tox/py27/local/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py", line 175, in operate
        return op(self.comparator, *other, **kwargs)
      File "/opt/stack/neutron/.tox/py27/local/lib/python2.7/site-packages/sqlalchemy/sql/operators.py", line 318, in __gt__
        return self.operate(gt, other)
      File "/opt/stack/neutron/.tox/py27/local/lib/python2.7/site-packages/sqlalchemy/orm/properties.py", line 269, in operate
        return op(self.__clause_element__(), *other, **kwargs)
      File "/opt/stack/neutron/.tox/py27/local/lib/python2.7/site-packages/sqlalchemy/sql/operators.py", line 318, in __gt__
        return self.operate(gt, other)
      File "/opt/stack/neutron/.tox/py27/local/lib/python2.7/site-packages/sqlalchemy/sql/elements.py", line 742, in operate
        return op(self.comparator, *other, **kwargs)
      File "/opt/stack/neutron/.tox/py27/local/lib/python2.7/site-packages/sqlalchemy/sql/operators.py", line 318, in __gt__
        return self.operate(gt, other)
      File "<string>", line 1, in <lambda>
      File "/opt/stack/neutron/.tox/py27/local/lib/python2.7/site-packages/sqlalchemy/sql/type_api.py", line 60, in operate
        return o[0](self.expr, op, *(other + o[1:]), **kwargs)
      File "/opt/stack/neutron/.tox/py27/local/lib/python2.7/site-packages/sqlalchemy/sql/default_comparator.py", line 53, in _boolean_compare
        "Only '=', '!=', 'is_()', 'isnot()' operators can "
    ArgumentError: Only '=', '!=', 'is_()', 'isnot()' operators can be used with None/True/False