Yesterday (2012-08-18) I upgraded RhodeCode 1.4.0b in order to verify the resolution of issue
#525. It worked, i.e., RC no longer stalled after having been configured to disallow anonymous access.
Now, when I access it I'm presented with the login form, as you can see in the first of the three screenshots I'm attaching to this issue.
However, when I log in I'm presented with the 404 error page that you can see in the second screenshot.
If then I manually strip off the path from the URL (/r/_admin/%2Fr%2F) and press enter, I can get to RC's main page, as you can see in the third screenshot.
I tried to log in as different users but everyone faced the same problem.
I also tried to log in from a pristine browser, without any cookies, but the problem remained.
I've reenabled anonymous access for now.