Title: Fixed mixed languages when some users have localized GUI and some not
Level: 1
Component: multisite
Compatible: compat
Version: 1.2.8b7
Date: 1458314348
Class: fix

When some of the GUI users are using a localized GUI and some are at the default
setting (have no explicit language configured), it could happen that the later
users sometimes see the GUI in the language another user has configured.
