title: Invalid default value - Django and python
body: <p>I have a model:</p>
  
  <pre><code>class Project(models.Model):
     project_id = models.CharField(max_length=200)
     project_name = models.CharField(max_length=200)
     description = models.CharField(max_length=20)
     PROJECT_TYPE_CHOICES = (
        ('E-Commerce','E-Commerce'),
        ('Business','Business'),
     )
  
    APPLICATION_TYPE_CHOICES = (
        ('Android','Android'),
        ('iOS','iOS'),
        ('Windows','Windows'),
    )
   project_type = models.CharField(max_length=2, choices=PROJECT_TYPE_CHOICES, 
   default='E-Commerce')
   application_type = models.CharField(max_length=3, 
   choices=APPLICATION_TYPE_CHOICES, default='Windows')
  
   def __str__(self):
      return self.project_name
  </code></pre>
  
  <p>when I do makemigrations it's working fine. but while does migrate it shows below error</p>
  
  <pre><code>django.db.utils.OperationalError: (1067, "Invalid default value for 
  'application
  _type'")
  </code></pre>