title: Django Programming error column does not exist even after running migrations
body: <p>I run <code>python manage.py makemigrations</code> and I get:
      No changes detected
  Then, <code>python manage.py migrate</code> and I get:
      No migrations to apply.</p>
  
  <p>Then, I try to push the changes to production:
      git push heroku master
      Everything up-to-date</p>
  
  <p>Then, in production, I repeat the command:
      heroku run python manage.py migrate
      No migrations to apply.</p>
  
  <p>Just in case, I run <code>makemigrations</code> in production:</p>
  
  <pre><code>heroku run python manage.py makemigrations
  No changes detected
  </code></pre>
  
  <p>WHY then I get a </p>
  
  <pre><code>ProgrammingError at ....
  
  column .... does not exist
  </code></pre>
  
  <p>"No changes detected" means the database is coherent with the code. 
  How can I debug this?¡?</p>