Tests failing with Python 3.8.2, pytest-5.3.5, py-1.8.1, pluggy-0.13.1

[mcepl]

When building the package for openSUSE package the test suite fails with the following tests:

[   32s] tests/test_sphinx.py::GenericTests::test_code FAILED                     [ 64%]
[   33s] tests/test_sphinx.py::GenericTests::test_headings FAILED                 [ 67%]
[   33s] tests/test_sphinx.py::GenericTests::test_image FAILED                    [ 71%]
[   33s] tests/test_sphinx.py::GenericTests::test_links FAILED                    [ 75%]
[   33s] tests/test_sphinx.py::GenericTests::test_lists FAILED                    [ 78%]
[   34s] tests/test_sphinx.py::CodeBlockTests::test_integration FAILED            [ 89%]
[   34s] tests/test_sphinx.py::IndentedCodeTests::test_integration FAILED         [ 92%]
[   34s] tests/test_sphinx.py::NestedHeaderBlock::test_integration FAILED         [ 96%]
[   34s] tests/test_sphinx.py::CustomExtensionTests::test_integration FAILED      [100%]

Complete _log
with all details is available.

[mgorny]

This is due to sphinx-3. Sphinx-2 has also one test failure but it seems harmless while these look like thing just don't work.