I use Django for my projects and I don't share this opinion on the maturity aspect. Can you explain your statement a bit more? What aspects of Django are immature?
There were plenty of extensions that allowed you to use Selenium with Django, I maintained one of them. Django is fairly conservative about including new features into the core that work well as extensions. And this is something I value a lot.
The time zone support, though, was really overdue.
Not really a fair feature comparison. If db migration wasn't in Rails, ActiveRecord wouldn't work the way it does. You can't say the same about Django's ORM.
Python suffers from their web framework community being too fragmented, so none of the projects are as mature as Rails.