When emerging with USE=doc, the emerge will fail when dev-python/sphinx_rtd_theme is not available. Reproducible: Always Steps to Reproduce: USE=doc emerge -v1 =ipython-7.16.1
Created attachment 648428 [details, diff] Add dev-python/sphinx_rtd_theme to dependencies to fix emerge with USE=doc.
Just checked that I still have the problem with ipython 7.19.0.
Fixed in all current versions in tree. Thanks for your report and patch.