Resolve conflict

[tuxcanfly]

When switching between feature branches, sometimes there can be conflict because the same migration number appears in both:

python manage.py migrate baz 0001
- Soft matched migration 0001 to 0001_initial.
Running migrations for baz:
! Migration baz:0002_auto__add_field_foo_bar2
should not have been applied
before baz:0002_auto__add_field_foo_bar1 but was.
InconsistentMigrationHistory: Inconsistent migration history
The following options are available:
    --merge: will just attempt the migration ignoring any potential
    dependency conflicts.

Need to think about a way to resolve this.

[tuxcanfly]

One minor issue is when a conflict happens (assume --no-merge) we should stop (or better rollback) the hook.

[dhuang]

Good point. Although probably much easier to check for a potential conflict beforehand, rather than trying to rollback after the conflict has been hit already.

[tuxcanfly]

You're right. Here's the scenario where merge conflict happens:

filesystem:

migrations/0002_a.py migrations/0002_b.py

south_migrationhistory table:

0002_b.py

now, south sees 0002_a.py on disk, but fails to find it in the database, so it says 0002_a.py should have run before 0002_b.py

Maybe we can pass --db-dry-run and check the exit status before proceeding...

[MoiTux]

I add this issues as well
I fixed it in my fork (in the branch fix_checkout_form_few_app), which avoid using the --merge option