As reported by many confused users at 
<http://git-annex.branchable.com/bugs/impossible_to_login_to_the_website_at_times/>
a successful login can end up at the error message "Error: Login succeeded,
but I don't remember why you were logging in [...]"

This happens when the user has earlier logged into a site on its https
url, but then later navigates to the http url, and is prompted to log in
there.

Workaround: Set `redirect_to_https`.