Changing Lua locale leads to a crash with some fonts

[Darkyenus]

Combination of this code

\begin{document}

\script{ os.setlocale("cs_CZ.utf-8") }
\font[filename=LinLibertine_R.otf]

foo

%\script{ os.setlocale("en_US.utf-8") } % Uncommenting this fixes it
\end{document}

with Linux Libertine font, causes a crash:

> sile localebug.sil
This is SILE 0.9.5.1
<localebug.sil>
[1] 
libtexpdf:fatal: CFF: Parsing CFF DICT failed. (error=-1)

The font works fine with default locale or when the locale is changed back at the end of the document. Some fonts work, some don't. Most (but not all) ttf fonts work, while most (but not all) otf fonts don't work.

[simoncozens]

OK, this is an upstream bug, albeit one that we need to fix. I will open a libtexpdf bug and we will track it there.