title: Django Migration Is Failing
body: <p>I have a django/postgresql application. Whenever I run my latest migration, I receive the following error:</p>
  
  <blockquote>
    <p>ValueError: Found wrong number (0) of constraints for package(speciality, title)</p>
  </blockquote>
  
  <p>I believe I need to customize the migration, but what change I should make.</p>
  
  <p>This is the migration:</p>
  
  <blockquote>
    <p>operations = [</p>
  
  <pre><code>    migrations.AddField(
  
          model_name='package',
  
          name='speciality',
  
          field=models.ManyToManyField(related_name='specialities', to='speciality.Speciality', blank=True),
  
      ),
  
      migrations.AlterField(
  
          model_name='package',
  
          name='title',
  
          field=models.CharField(unique=True, max_length=50),
  
      ),
  
      migrations.AlterUniqueTogether(
  
          name='package',
  
          unique_together=set([]),
  
      ),
  
      migrations.RemoveField(
  
          model_name='package',
  
          name='speciality',
  
      ),
  
  ]
  </code></pre>
  </blockquote>
  
  <p>This is my current table configuaration for this model:</p>
  
  <blockquote>
    <p>sleepyfish=# \d package
                                         Table "public.package"
        Column     |           Type           |                      Modifiers<br>
    ---------------+--------------------------+------------------------------------------------------  id            | integer                  | not null default
    nextval('package_id_seq'::regclass)  created_at    | timestamp with
    time zone | not null  updated_at    | timestamp with time zone | not
    null  title         | character varying(50)    | not null  description
    | text                     |   status        | boolean<br>
    | not null  price         | numeric(8,2)             | not null 
    speciality_id | integer                  |  Indexes:
        "package_pkey" PRIMARY KEY, btree (id)
        "package_speciality_id_3aeb5c97679442e4_uniq" UNIQUE CONSTRAINT, btree (speciality_id, title)
        "package_66db61fe" btree (speciality_id) Foreign-key constraints:
        "package_speciality_id_4255b58fe1ae00c0_fk_speciality_id" FOREIGN KEY (speciality_id) REFERENCES speciality(id) DEFERRABLE INITIALLY
    DEFERRED Referenced by:
        TABLE "claimedpackage" CONSTRAINT "claimedpackage_package_id_9e1da358fbb9a46_fk_package_id" FOREIGN KEY
    (package_id) REFERENCES package(id) DEFERRABLE INITIALLY DEFERRED
        TABLE "package_service" CONSTRAINT "package_service_package_id_3b0ea08bfcd8da76_fk_package_id" FOREIGN
    KEY (package_id) REFERENCES package(id) DEFERRABLE INITIALLY DEFERRED</p>
  </blockquote>