Use case:
1. Have multiple languages enabled
2. Have a switch language block in a (global) area in the top of the page with the standard flags template
3. Go to /login or /register -> you get the language you came from
4. Refresh page -> you get the last language from the language selector

Reason:
The flags-template uses the resolve_language_url-function.
That function SETS the locale when the current page is a system page.
In this case it will set the locale for each language in the switch language block.

Happens in the latest version of Concrete8

Solution:
- Adjust the template to avoid the "resolve_language_url"-function
or
- Remove setting the locale in that function