New/reset installation fails when there's an existing login cookie for the user

[ZeiP]

It causes an error message like

ActiveRecord::RecordNotFound (Couldn't find User with 'id'=1):
lib/login_system.rb:148:in `get_current_user'
lib/login_system.rb:105:in `login_required'
lib/login_system.rb:86:in `login_or_feed_token_required'

This seems to be caused by the browser returning a login cookie, which causes Tracks to think the user is already logged in but failing to find a matching user.