I've stopped citing Instagram as an example of Django scaling after learning from one of their engineering managers at PyCon 2015 that they're running a heavily

I've stopped citing Instagram as an example of Django scaling after learning from one of their engineering managers at PyCon 2015 that they're running a heavily modified internal fork of Django 1.5 or 1.6. It sounds like they really have built their own framework (before today's Django + DRF existed). Maybe this has changed post Facebook acquisition. I know Facebook is mostly on Python 3 and modern stuff now.