Fixed #17424 -- annotate() + exclude() bug

The bug was already fixed by 01b9c3d519,
so only tests added.

At the same time promote_joins()'s uncoditional flag is gone, it isn't
needed for anything any more.

tests/aggregation/tests.py

@@ -596,3 +596,24 @@ class BaseAggregateTestCase(TestCase):
         self.assertEqual(
             max_books_per_rating,
             {'books_per_rating__max': 3})
+
+    def test_ticket17424(self):
+        """
+        Check that doing exclude() on a foreign model after annotate()
+        doesn't crash.
+        """
+        all_books = list(Book.objects.values_list('pk', flat=True).order_by('pk'))
+        annotated_books = Book.objects.order_by('pk').annotate(one=Count("id"))
+
+        # The value doesn't matter, we just need any negative
+        # constraint on a related model that's a noop.
+        excluded_books = annotated_books.exclude(publisher__name="__UNLIKELY_VALUE__")
+
+        # Try to generate query tree
+        str(excluded_books.query)
+
+        self.assertQuerysetEqual(excluded_books, all_books, lambda x: x.pk)
+
+        # Check internal state
+        self.assertIsNone(annotated_books.query.alias_map["aggregation_book"].join_type)
+        self.assertIsNone(excluded_books.query.alias_map["aggregation_book"].join_type)