In Django, if you say managed = False in a model's Meta, you tell Django not to touch the database table. So: no automatic database migrations, for instance.
Now, what is the problem if you have managed = False, and Django does do migrations?
Some of you will have seen the error already.
The comma after False is the problem:
>>> a = False, >>> a (False,) >>> bool(a) True
The comma turns it into a tuple. And a non-empty tuple evaluates to True!
I found it quite funny. My colleague was torn between "extremely relieved" and "extremely annoyed" :-)