PostgreSQL + Django AutoField id doesn't get restarted after flush

Question

I am currently testing Django project using django-nose. I use PostgreSQL for my DB. The problem I am facing is:

In test setUp method I create one Emp instance and save it. Then I execute this:

Emp.objects.filter(empId=1)

but this doesn't exist. During debugging I figured that the Emp instance exists in DB but its ID is 137.

I presume that is the issue with django-nose as it flushes DB after every test, however previous empId's seem to remain.

Note: I am using:

class Emp(models.Model):
    empId = models.AutoField(primary_key=True)

My question is, how do I resolve this issue? Is there a way to restart id auto-increment routine after every setUp call?