Steps to reproduce the issue

1. Use the current version of Joomla! 3.7.0-alpha2
2. Start a installation and select Danish as installation language.
3. See that the language of the page does not change to Danish.

Expected result

The language should change form English to Danish.

See also: joomla-projects/joomla-browser#127

System information (as much as possible)

PHP Built On Linux acer 4.4.0-57-generic #78-Ubuntu SMP Fri Dec 9 23:50:32 UTC 2016 x86_64
Database Version 5.7.16-0ubuntu0.16.04.1
Database Collation utf8_general_ci
Database Connection Collation utf8mb4_general_ci
PHP Version 7.0.8-0ubuntu0.16.04.3
Web Server Apache/2.4.18 (Ubuntu)
WebServer to PHP Interface apache2handler
Joomla! Version Joomla! 3.7.0-alpha2 dev [ Amani ] 20-December-2016 23:59 GMT
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0