Language "ngerman" does not translate the caption names

[sscherfke]

If I use polyglossia with lualatex and set the main language to ngerman, captions for, e.g., the table of contents are not translated (e.g., to Inhaltsverzeichnis). It works, however, if I use german:

\usepackage{polyglossia}
\setmainlangauge{ngerman}  % -> "Contents"
\setmainlanguage{german}  % -> "Inhaltsverzeichnis"

\begin{document}

\tableofcontents
\chapter{Hello, world!}
Ohai

\end{document}

However, using german does not work on Fedora 26 (but on Fedora 27).

See: sphinx-doc/sphinx#4717

[jspitz]

@sscherfke since this turned out to be a bug in sphinx, I suggest you close this ticket.