[Koha] Vietnamese language choice in OPAC appears in Chinese characters

[Daniel Owens]

We have used Koha in Vietnam for several years, and when the vi-VN 
locale is installed, it appears in the OPAC as Chinese characters. Not 
the actual interface, mind you, just in the language selector:

<a href="/cgi-bin/koha/opac-changelanguage.pl?language=vi-VN" 
tabindex="-1" role="menuitem" class="listmenulink">㗂越</a>

That seems to be a bug to me, but maybe there is an explanation? Is 
there a way to fix it? It should be "Tiếng Việt" not "㗂越".

Daniel