This is the story of how I thought I'd spend an hour or so, maybe two, fixing it so that when people press the "Place Order" button on the
/preview page, they get sent to the
/thank-you page. I started at around 10-11am. I sort of worked it out at around 11.25pm.
Update 18 Apr 2018: Checkout Express doesn't automatically log customers out after payment. As far as I know, and according to this issue, there is presently no solution. What a nightmare scenario. Take this into consideration if you still want to use it.
I thought I'd need to override Oscar's checkout views to integrate Paypal. As it turns out, I don't have to. But, since I've already done it and figured out that it has a particular naughty quirk, I might as well publish this.
I realised today that if Mezzanine and Oscar share the same file names for a lot of templates and static files (in addition to urls, as mentioned in part 1), I should probably separate them more clearly. Especially since static files are collected into the same directory for production with