Can't log in to www.autosport.com from TorBrowser

When I complete the login fields on the frontpage at www.autosport.com and click login, the page refreshes and looks exactly as before, still requesting a login.

The reasons I think this is a TorBrowser bug are:

• I can log in from Orweb/Orbot on Android after enabling all cookies. (I enabled all cookies because Orweb's whitelist has issues). -- This rules out the site attempting to block Tor and problems relate to use of plug-ins like flash.
• If, after the login attempt, I view the cookies in TorBrowser I can see all the cookies set by autosport.com, storing my correct account information.

It seems as if for some reason this site's scripts are unable to read the site's stored cookies so it acts as if not logged in.

I tried the latest TorBrowser 3.0 alpha 2 and the bug persists there. I am running on OSX 10.7.5.

Trac:
Username: msfc