Checkout doesn't redirect to /checkout/mustlogin?next=... correctly

[arrkaye]

This was working in an earlier revision of 0.9.3, but seems to have broken on HEAD.

Issue is that when I have 'Only authenticated users can check out' enabled, it used to redirect to /checkout/mustlogin?next=/checkout to force the user to login.

With the latest development build, satchmo does hit the redirect code in (apps/payment/views/contact.py:82) but the browser goes straight to /checkout.

Have tried this on a fresh install of a store with the same result.

ARK