[Answered ]-Blank responses from Django runserver when checking user permissions

As saying in the second link in your post, especially http://forum.nginx.org/read.php?2,196581 : when you works w/ Nginx and uWSGI and get a non-empty POST, always read the request.POST before return an HttpResponse. The reason is described in the link.
You don’t have to override an handler, just put the request.POST line before the return code, or inside some decorator or middleware.
I encountered this issue for production site half a year ago and put the line in a middleware to solve it.