[2.1.x] Fixed #29643 -- Fixed crash when combining Q objects with __in lookups and lists.

Regression in fc6528b2.
Backport of 9fee2298 from master

django/utils/tree.py

@@ -71,7 +71,10 @@ class Node:
         )
 
     def __hash__(self):
-        return hash((self.__class__, self.connector, self.negated) + tuple(self.children))
+        return hash((self.__class__, self.connector, self.negated) + tuple([
+            tuple(child) if isinstance(child, list) else child
+            for child in self.children
+        ]))
 
     def add(self, data, conn_type, squash=True):
         """

docs/releases/2.1.1.txt

@@ -18,3 +18,6 @@ Bugfixes
 * Fixed a regression in Django 2.0 where using ``manage.py test --keepdb``
   fails on PostgreSQL if the database exists and the user doesn't have
   permission to create databases (:ticket:`29613`).
+
+* Fixed a regression in Django 2.0 where combining ``Q`` objects with ``__in``
+  lookups and lists crashed (:ticket:`29643`).

tests/utils_tests/test_tree.py

@@ -23,10 +23,12 @@ class NodeTests(unittest.TestCase):
         node3 = Node(self.node1_children, negated=True)
         node4 = Node(self.node1_children, connector='OTHER')
         node5 = Node(self.node1_children)
+        node6 = Node([['a', 1], ['b', 2]])
         self.assertNotEqual(hash(self.node1), hash(self.node2))
         self.assertNotEqual(hash(self.node1), hash(node3))
         self.assertNotEqual(hash(self.node1), hash(node4))
         self.assertEqual(hash(self.node1), hash(node5))
+        self.assertEqual(hash(self.node1), hash(node6))
         self.assertEqual(hash(self.node2), hash(Node()))
 
     def test_len(self):