Failure (ValueError) when running on Python 3.8

[jaraco]

When running on Python 3.8:

.tox/python/lib/python3.8/site-packages/pluggy/hooks.py:286: in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
.tox/python/lib/python3.8/site-packages/pluggy/manager.py:92: in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
.tox/python/lib/python3.8/site-packages/pluggy/manager.py:83: in <lambda>
    self._inner_hookexec = lambda hook, methods, kwargs: hook.multicall(
.tox/python/lib/python3.8/site-packages/_pytest/runner.py:125: in pytest_runtest_call
    item.runtest()
.tox/python/lib/python3.8/site-packages/pytest_checkdocs.py:17: in runtest
    self.rst2html(self.get_long_description())
.tox/python/lib/python3.8/site-packages/pytest_checkdocs.py:44: in get_long_description
    desc = self._find_local_distribution().metadata['Description']
.tox/python/lib/python3.8/site-packages/pytest_checkdocs.py:39: in _find_local_distribution
    dist, = importlib_metadata.distributions(path=['.', 'src'])
E   ValueError: too many values to unpack (expected 1)

The problem is that importlib_metadata and importlib.metadata are interfering and breaking assumptions.