LLDP tests fail with construct error

The ironic-inspector LLDP tests are failing in master for py27 with the construct lib error below. This problem was not happening in Queens and appears to be due to change in construct lib. This was seen with construct==2.9.35.

  Traceback (most recent call last):
    ImportError: Failed to import test module: ironic_inspector.test.unit.test_plugins_local_link_connection
    Traceback (most recent call last):
      File "/home/bfournie/workspace/ironic-inspector/.tox/py27/lib/python2.7/site-packages/unittest2/loader.py", line 456, in _find_test_path
        module = self._get_module_from_name(name)
      File "/home/bfournie/workspace/ironic-inspector/.tox/py27/lib/python2.7/site-packages/unittest2/loader.py", line 395, in _get_module_from_name
        __import__(name)
      File "ironic_inspector/test/unit/test_plugins_local_link_connection.py", line 18, in <module>
        from ironic_inspector.plugins import local_link_connection
      File "ironic_inspector/plugins/local_link_connection.py", line 23, in <module>
        from ironic_inspector.common import lldp_parsers
      File "ironic_inspector/common/lldp_parsers.py", line 22, in <module>
        from ironic_inspector.common import lldp_tlvs as tlv
      File "ironic_inspector/common/lldp_tlvs.py", line 137, in <module>
        mapping_for_switch(CHASSIS_ID_MAPPING)))
      File "/home/bfournie/workspace/ironic-inspector/.tox/py27/lib/python2.7/site-packages/construct/core.py", line 1876, in __init__
        self.subcons = mergefields(*subcons)
      File "/home/bfournie/workspace/ironic-inspector/.tox/py27/lib/python2.7/site-packages/construct/core.py", line 157, in mergefields
        result.extend(select(sc))
      File "/home/bfournie/workspace/ironic-inspector/.tox/py27/lib/python2.7/site-packages/construct/core.py", line 149, in select
        return select(sc.subcon)
      File "/home/bfournie/workspace/ironic-inspector/.tox/py27/lib/python2.7/site-packages/construct/core.py", line 149, in select
        return select(sc.subcon)
      File "/home/bfournie/workspace/ironic-inspector/.tox/py27/lib/python2.7/site-packages/construct/core.py", line 152, in select
        raise ConstructError("Embedding only works with: Struct, Sequence, FocusedSeq, Union")
    ConstructError: Embedding only works with: Struct, Sequence, FocusedSeq, Union

The error is coming from this definition:
ChassisId = core.Struct(
    'subtype' / core.Enum(core.Byte, **mapping_for_enum(
        CHASSIS_ID_MAPPING)),
    'value' /
    core.Embedded(core.Switch(construct.this.subtype,
                              mapping_for_switch(CHASSIS_ID_MAPPING)))
)

It looks like the behavior of "Embedded" has changed such that "Switch" can no longer be embedded in a Struct.