Unhashable type Point bug with multiple annotations

[Lachlan Cannon]

Simplified example to reproduce, with these models:

class State(models.Model):
    name = models.CharField(max_length=100)

class Location(models.Model):
    name = models.CharField(max_length=100)
    location = models.PointField(geography=True)
    state = models.ForeignKey(State, on_delete=models.CASCADE)

Running the following code works fine in 2.0 (assuming you have a few models set up):

State.objects.annotate(distance=Distance('locality__location', Locality.objects.first().location))

But this code works in 1.11, and fails in 2.0.1 with TypeError: unhashable type: 'Point':

State.objects.annotate(distance=Distance('locality__location', self.locality.location)).annotate(count=Count('locality'))