Signed in user can access Login page

Steps to reproduce:

1. Open Login page
2. enter some invalid data or just leave it blank and click Sign In to see the error message
3. Click on Sign In in the header
   Login pop-up dialog is opened
4. Login with some user

Actual Result: user is logged in (you can see the username in the header), but login page is still shown
Expected result: User should be redirected to the main page.

Note that "resend query" dialog is opened after step 4.
Issue wasn't reproduced in Chrome