[manifolds] Exception occurred:
[manifolds]   File "/nix/store/ldl3rb92yvl070c7q3nnjgwl5mdx2wvb-python3.7-sphinx-2.0.0/lib/python3.7/site-packages/sphinx/ext/intersphinx.py", line 207, in load_mappings
[manifolds]     for key, (name, (uri, invs)) in app.config.intersphinx_mapping.items():
[manifolds] ValueError: too many values to unpack (expected 2)
[manifolds] The full traceback has been saved in /build/sphinx-err-e6h8o39l.log, if you want to report the issue to the developers.
[manifolds] Please also report this if it was a user error, so that a better error message can be provided next time.
[manifolds] A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
Traceback (most recent call last):
  File "/nix/store/9894fxjpg8v99j14kip6b13rdfgf4m5k-python3-3.7.5/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/nix/store/9894fxjpg8v99j14kip6b13rdfgf4m5k-python3-3.7.5/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/nix/store/i0gjbmskaxkmj2qif96ayvb803l6hm4k-python3.7-sagelib-9.0.beta6/lib/python3.7/site-packages/sage_setup/docbuild/sphinxbuild.py", line 328, in <module>
    runsphinx()
  File "/nix/store/i0gjbmskaxkmj2qif96ayvb803l6hm4k-python3.7-sagelib-9.0.beta6/lib/python3.7/site-packages/sage_setup/docbuild/sphinxbuild.py", line 317, in runsphinx
    sys.stderr.raise_errors()
  File "/nix/store/i0gjbmskaxkmj2qif96ayvb803l6hm4k-python3.7-sagelib-9.0.beta6/lib/python3.7/site-packages/sage_setup/docbuild/sphinxbuild.py", line 252, in raise_errors
    raise OSError(self._error)
OSError: Exception occurred:
Error building the documentation.
Traceback (most recent call last):
  File "/nix/store/9894fxjpg8v99j14kip6b13rdfgf4m5k-python3-3.7.5/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/nix/store/9894fxjpg8v99j14kip6b13rdfgf4m5k-python3-3.7.5/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/nix/store/i0gjbmskaxkmj2qif96ayvb803l6hm4k-python3.7-sagelib-9.0.beta6/lib/python3.7/site-packages/sage_setup/docbuild/__main__.py", line 2, in <module>
    main()
  File "/nix/store/i0gjbmskaxkmj2qif96ayvb803l6hm4k-python3.7-sagelib-9.0.beta6/lib/python3.7/site-packages/sage_setup/docbuild/__init__.py", line 1671, in main
    builder()
  File "/nix/store/i0gjbmskaxkmj2qif96ayvb803l6hm4k-python3.7-sagelib-9.0.beta6/lib/python3.7/site-packages/sage_setup/docbuild/__init__.py", line 310, in _wrapper
    getattr(get_builder(document), name)(*args, **kwds)
  File "/nix/store/i0gjbmskaxkmj2qif96ayvb803l6hm4k-python3.7-sagelib-9.0.beta6/lib/python3.7/site-packages/sage_setup/docbuild/__init__.py", line 504, in _wrapper
    build_many(build_ref_doc, L)
  File "/nix/store/i0gjbmskaxkmj2qif96ayvb803l6hm4k-python3.7-sagelib-9.0.beta6/lib/python3.7/site-packages/sage_setup/docbuild/__init__.py", line 258, in build_many
    _build_many(target, args, processes=NUM_THREADS)
  File "/nix/store/i0gjbmskaxkmj2qif96ayvb803l6hm4k-python3.7-sagelib-9.0.beta6/lib/python3.7/site-packages/sage_setup/docbuild/utils.py", line 283, in build_many
    raise worker_exc.original_exception