Fixed #14754 -- corrected using an aggregate in an F expressions when that...

    def relabel_aliases(self, change_map):

        for node, col in self.cols.items():

            if hasattr(col, "relabel_aliases"):

                col.relabel_aliases(change_map)

            else:

                self.cols[node] = (change_map.get(col[0], col[0]), col[1])

    #####################################################

# coding: utf-8

import pickle

from django.db import connection, models, DEFAULT_DB_ALIAS

from django.conf import settings

from django.db import models

class Author(models.Model):

    def __unicode__(self):

        return self.name

class Entries(models.Model):

    EntryID = models.AutoField(primary_key=True, db_column='Entry ID')

    Entry = models.CharField(unique=True, max_length=50)

import datetime

import pickle

from decimal import Decimal

from operator import attrgetter

from django.core.exceptions import FieldError

from django.conf import settings

from django.test import TestCase, Approximate, skipUnlessDBFeature

from django.db import DEFAULT_DB_ALIAS

from django.db.models import Count, Max, Avg, Sum, StdDev, Variance, F

from regressiontests.aggregation_regress.models import *

from models import Author, Book, Publisher, Clues, Entries, HardbackBook

class AggregationTests(TestCase):

        # Regression for #10197 -- Queries with aggregates can be pickled.

        # First check that pickling is possible at all. No crash = success

        qs = Book.objects.annotate(num_authors=Count('authors'))

        out = pickle.dumps(qs)

        pickle.dumps(qs)

        # Then check that the round trip works.

        query = qs.query.get_compiler(qs.db).as_sql()[0]

            Author.objects.count()

        )

    def test_f_expression_annotation(self):

        # Books with less than 200 pages per author.

        qs = Book.objects.values("name").annotate(

            n_authors=Count("authors")

        ).filter(

            pages__lt=F("n_authors") * 200

        ).values_list("pk")

        self.assertQuerysetEqual(

            Book.objects.filter(pk__in=qs), [

                "Python Web Development with Django"

            ],

            attrgetter("name")

        )

    @skipUnlessDBFeature('supports_stddev')

    def test_stddev(self):

        self.assertEqual(