How reproducible:
Always

Steps to Reproduce:
1. With RBAC enabled login as superuser
2. Open Run as Role dialog (in my case in right upper corner navigate superuser -> Run as SuperUser) 
3. Select role, click Run As
4. You are asked to confirm application reload, click Cancel

Actual results:
browser is reloaded

Expected results:
There either shoudn't be Cancel button 
or if the button should be there the browser shouldn't be refreshed if the button is clicked.