Django 1.8, Django Slumber and Django Async

I found this article very frustrating. It makes a number of claims, but doesn't provide any detail to allow me to understand what the author is actually complainging about.

The biggest change in 1.7 was the alteration of Django's transaction handling.

How did it change?

[...] it seems to me that the defaults for new projects are still broken and unsafe [...]

What is unsafe about the defaults?

This unsafe-by-default behaviour is compounded by the difficulty of testing transactions in Django

Why is this difficult? An example would be useful.

the behaviour you get would be what you'd probably expect

Expect from what? Other systems I've used left the transactions completely up to the developer, I was happy that Django was willing to help at all with it.

Good general critique about the default behaviour of Django transactions and feasibility of automated testing.