Models migration with change field foreign to many and deleting unique together.

Description

	(last modified by Simon Charette)

I have models like
class Authors(models.Model):
project_data_set = models.ForeignKey(
ProjectDataSet,
on_delete=models.PROTECT
)
state = models.IntegerField()
start_date = models.DateField()
class Meta:
unique_together = (('project_data_set', 'state', 'start_date'),)
and
class DataSet(models.Model):
name = models.TextField(max_length=50)
class Project(models.Model):
data_sets = models.ManyToManyField(
DataSet,
through='ProjectDataSet',
)
name = models.TextField(max_length=50)
class ProjectDataSet(models.Model):
"""
Cross table of data set and project
"""
data_set = models.ForeignKey(DataSet, on_delete=models.PROTECT)
project = models.ForeignKey(Project, on_delete=models.PROTECT)
class Meta:
unique_together = (('data_set', 'project'),)
when i want to change field project_data_set in Authors model from foreign key field to many to many field I must delete a unique_together, cause it can't be on many to many field.
Then my model should be like:
class Authors(models.Model):
project_data_set = models.ManyToManyField(
ProjectDataSet,
)
state = models.IntegerField()
start_date = models.DateField()
But when I want to do a migrations.
python3 manage.py makemigrations
python3 manage.py migrate
I have error:
ValueError: Found wrong number (0) of constraints for app_authors(project_data_set, state, start_date)
The database is on production, so I can't delete previous initial migrations, and this error isn't depending on database, cause I delete it and error is still the same.
My solve is to first delete unique_together, then do a makemigrations and then migrate. After that change the field from foreign key to many to many field, then do a makemigrations and then migrate.
But in this way I have 2 migrations instead of one.
I added attachment with this project, download it and then do makemigrations and then migrate to see this error.