Autogmatic class generation for AlignedDynamicTable fails

[oruebel]

Description

This issue has come up as part of #551 to integrated AlignedDynamicTable which is a DynamicTable that itself contains other DynamicTable objects. Due #553 integrating AlignedDynamicTable triggered the automatic class generation for that type. The automatic class generation for AlignedDynamicTable , however, fails on the current HDMF dev branch. It appears that the automatic class generation attempts to use both DynamicTable and MultiContainerInterface as a base type for AlignedDynamicTable which appear to result into a conflict with regard to method resolution order. Specifically the type of error I am seeing is:

ImportError: Failed to import test module: validator_tests.test_validate
Traceback (most recent call last):
  File "/Users/oruebel/anaconda3/envs/icephys-port/lib/python3.8/unittest/loader.py", line 436, in _find_test_path
    module = self._get_module_from_name(name)
  File "/Users/oruebel/anaconda3/envs/icephys-port/lib/python3.8/unittest/loader.py", line 377, in _get_module_from_name
    __import__(name)
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/tests/unit/validator_tests/test_validate.py", line 10, in <module>
    from hdmf.testing import TestCase
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/testing/__init__.py", line 1, in <module>
    from .testcase import TestCase, H5RoundTripMixin  # noqa: F401
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/testing/testcase.py", line 11, in <module>
    from ..common import validate as common_validate, get_manager
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/common/__init__.py", line 109, in <module>
    load_namespaces(__resources['namespace_path'])
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/utils.py", line 584, in func_call
    return func(**pargs)
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/common/__init__.py", line 97, in load_namespaces
    return __TYPE_MAP.load_namespaces(namespace_path)
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/utils.py", line 580, in func_call
    return func(args[0], **pargs)
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/build/manager.py", line 477, in load_namespaces
    container_cls = self.get_container_cls(src_ns, dt)
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/utils.py", line 580, in func_call
    return func(args[0], **pargs)
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/build/manager.py", line 505, in get_container_cls
    cls = self.__class_generator.generate_class(data_type, spec, parent_cls, attr_names, self)
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/utils.py", line 580, in func_call
    return func(args[0], **pargs)
  File "/Users/oruebel/Devel/nwb/icephys_extensions/port_to_nwb/hdmf/src/hdmf/build/classgenerator.py", line 79, in generate_class
    cls = ExtenderMeta(data_type, tuple(bases), classdict)
  File "/Users/oruebel/anaconda3/envs/icephys-port/lib/python3.8/abc.py", line 85, in __new__
    cls = super().__new__(mcls, name, bases, namespace, **kwargs)
TypeError: Cannot create a consistent method resolution
order (MRO) for bases MultiContainerInterface, DynamicTable

I implemented a hackish workaround in 09e4cac to avoid the automatic class generation for AlignedDynamicTable so that I could proceed with implementation of the PR and testing, but this is not the appropriate fix.

Steps to Reproduce

• Check out the branch from this PR Add/aligned dynamic table #551
• Comment out the following change 09e4cac
• Simply try to import the class, i.e., from hdmf.common import AlignedDynamicTable

Environment

Python Executable: Install from branch https://github.com/hdmf-dev/hdmf/pull/551
Python Version: Python  3.8
Operating System:  macOS 
HDMF Version: dev with modifications from https://github.com/hdmf-dev/hdmf/pull/551

Checklist

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