Browser translation missing public area under Linux
$ ruby script/about
Redmine version 2.3.4.stable
Ruby version 2.1.0-p0 (2013-12-25) [x86_64-linux]
Rails version 3.2.13
Database adapter Mysql2
The problem is best illustrated by the provided screenshot. I've found no reference only about this particular problem, besides that there is 1 site which also displays this particular way for me.
Do note that this does not happen on any windows browser that is viewing the login portal: the problem is exclusively Linux and the way Linux browsers (Chrome/Firefox) probably "tell" which language they are using.
Obviously (since displayed correctly under Windows) there is nothing wrong with the translation files.