Comment # 23 on bug 1174184 from Wolfgang Rosenauer

So to summarize a bit:
- we changed the way how langpacks are packaged in 78.0.2 because the old way
was not working correctly anymore
- apparently Firefox has an issue with picking up these changes which are
unexpected to me. This case should be handled more gracefully from Firefox

So by our change we triggered from my point of view an issue existing in
Firefox upstream.
The problem is that a fix might be non-trivial but the workaround more or less
is. I will report that case upstream to see if something can be done.