warnings.warn('Matplotlib is building the font cache using fc-list. This may take a moment.')
loading pickled environment... failed: ('__init__() takes exactly 4 arguments (1 given)', <class 'sphinx.environment.BuildEnvironment'>, ())
Warning, treated as error:
WARNING: latex_use_modeindex is deprecated. Use latex_domain_indices instead.
While testing #2399 saw them all failing... a sample env fails with