pk attribute not set when having own primary key

[eng. Ilian Iliev]

Example:

# models.py
class Language(models.Model):
    language = models.IntegerField(primary_key=True)
    code = models.CharField(verbose_name='Language code (2 chars)', blank=False, max_length=2)

# views.py
l = Language.objects.create(code='x')
print l.pk  # return None

The above mention problem happens only if we have "primary_key=True"