ASA-2019-00402 – Django: Incorrect HTTP detection with reverse-proxy connecting via HTTPS

When deployed behind a reverse-proxy connecting to Django via HTTPS, django.http.HttpRequest.scheme would incorrectly detect client requests made via HTTP as using HTTPS. This entails incorrect results for is_secure(), and build_absolute_uri(), and that HTTP requests would not be redirected to HTTPS in accordance with SECURE_SSL_REDIRECT.