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Changes between Version 9 and Version 10 of Ticket #10244, comment 19

v9	v10
29	29	- `MyModel.objects.create(my_filefield=None).my_filefield is not None`
30	30	- `my_model_instance.my_filefield` is always "truthy", so we need to check e.g. `my_filefield.name` ([https://stackoverflow.com/q/8850415 example])
31		- we cannot use the `__isnull` field lookup, but have to check for equality with the empty string ~~`''`, or even `not in~~ ['', None]` ([https://stackoverflow.com/q/4771464 example])
	31	- we cannot use the `__isnull` field lookup, but have to check for equality with the empty string (`my_filefield=''`), or even `my_filefield__in=['', None]` ([https://stackoverflow.com/q/4771464 example])
32	32	- `FileField(null=True, unique=True)` is broken, because the database entry is `''` instead of `null`, so we get a unique-constraint violation if we try to create another instance with `None`
33	33