Migrations do not ignore unmanaged models (unlike syncdb)

[Tim Graham]

Migrations do not ignore ​unmanaged models. To reproduce, simply add:

    class Meta:
        managed=False

to the models in the tutorial and then

python manage.py makemigrations polls
python manage.py migrate

You will see tables are created for these models unlike doing the same and running syncdb.

[loic84]

PR ​https://github.com/django/django/pull/2474.

[Tim Graham <timograham@…>]

In 69d4b1c3ea64f298380b0531c34509ae5eec89b9:

Fixed #22331 -- Fixed migrations ProjectState to ignore unmanaged models.

[Tim Graham <timograham@…>]

In bf69375c4d2eaec4f00c646b9e7e84a9397d1a20:

[1.7.x] Fixed #22331 -- Fixed migrations ProjectState to ignore unmanaged models.

Backport of 69d4b1c3ea from master

[Tim Graham <timograham@…>]

In d84beb3d9105300a94061dd94911a0c3cd9021d2:

Revert "[1.7.x] Fixed #22331 -- Fixed migrations ProjectState to ignore unmanaged models."

This reverts commit bf69375c4d2eaec4f00c646b9e7e84a9397d1a20.

[Tim Graham <timograham@…>]

In 42336c84a0daedfd8242333622eefe202e32398e:

Fixed #22331 -- Made MigrationAutodetector ignore unmanaged models.

This commit reverts 69d4b1c and tackle the issue from a different angle.
Models remain present in the project state, but are now ignored by the
autodetector.

[Tim Graham <timograham@…>]

In 39fc8d4b8e94d9e019148ce9d287e72b3363a7bf:

[1.7.x] Fixed #22331 -- Made MigrationAutodetector ignore unmanaged models.

This commit reverts 69d4b1c and tackle the issue from a different angle.
Models remain present in the project state, but are now ignored by the
autodetector.

Backport of 42336c84a0daedfd8242333622eefe202e32398e from master