Add a migration to ensure EmailAddress model populated

Many users on production have User.email set with no corresponding email address model

itou/users/migrations/0015_ensure_emailaddress_model_use.py

@@ -0,0 +1,38 @@
+from django.db import migrations
+from django.db.models import OuterRef, Subquery
+
+
+def create_email_addresses_for_users(apps, schema_editor):
+    User = apps.get_model("users", "User")
+    EmailAddress = apps.get_model("account", "EmailAddress")
+
+    # Get all those values of User.email where there is no corresponding EmailAddresses instance
+    users_missing_addresses = (
+        User.objects.prefetch_related("emailaddress_set")
+        .annotate(email_exists=Subquery(EmailAddress.objects.filter(email=OuterRef("email")).values("id")[:1]))
+        .filter(email_exists__isnull=True)
+        .values_list("user", "email")
+    )
+
+    EmailAddress.objects.bulk_create(
+        EmailAddress(user=x.user, email=x.email, primary=True, verified=True) for x in users_missing_addresses
+    )
+
+
+class Migration(migrations.Migration):
+    """
+    This migration was created at a time when not all User email addresses had an associated EmailAddress.
+    It ensures that EmailAddress instances are created where they are not existing.
+    Of course this means that the migration can be squashed later.
+    """
+
+    dependencies = [
+        ("users", "0014_alter_jobseekerprofile_birthdate__add_index"),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            create_email_addresses_for_users,
+            reverse_code=migrations.RunPython.noop,
+        ),
+    ]