There is an undocumented utils
versions module in Django:
https://github.com/django/django/blob/master/django/utils/version.py
With that, you can get the normal version as a string or a detailed version tuple:
>>> from django.utils import version
>>> version.get_version()
... 1.9
>>> version.get_complete_version()
... (1, 9, 0, 'final', 0)