I am definitely having this problem on my private repository. Whichever highlight style I choose, and however many indent spaces I pick in my admin page, I always get 8-space tabs in my source browser.
Was going to file bug report about it and saw this one. No matter the indent spaces setting, I always get 8-space tabs in source browser.
Also, I would like to suggest this be a global setting for the user - that no matter what repo you are viewing, public or private, your color and indent preferences will apply to the code you are viewing.