title: Django model inheritance, overriding fields
body: <p>I am reading the book Python Web Development with Django and I found this example in the book:</p>
  
  <pre><code> class Book(models.Model):
              title = models.CharField(max_length=100)
              genre = models.CharField(max_length=100)
              num_pages = models.IntegerField()
              authors = models.ManyToManyField(Author)
  
              def __unicode__(self):
                  return self.title
  
      class SmithBook(Book):
          authors = models.ManyToManyField(Author, limit_choices_to={'name__endswith': 'Smith'})
  </code></pre>
  
  <p>It seems like it is not working: </p>
  
  <blockquote>
    <p>FieldError: Local field 'authors' in class 'SmithBook' clashes with field of similar name from base class 'Book'</p>
  </blockquote>
  
  <p>I am using Django 1.5.3 and the book is for Django 1.0.</p>
  
  <p>Why it is not possible to override fields when inherit in Django? Was it possible in Django 1.0, or it is an error in the book?</p>