Your interviewers were likely unaware that changes were made in Django 1.6+ to resolve issues related to transaction management, including a new atomic method, where previously one would use commit_on_success.

References

Django 1.6 changelog:
https://docs.djangoproject.com/en/3.1/releases/1.6/#transaction-management-apis

Django 1.6 transaction documentation (with 1.5 transaction deprecation notices): https://django.readthedocs.io/en/1.6.x/topics/db/transactions.html