Add test_load_build_falsey_state

Added 6 tests where the `state` is falsey but not None, and the `inst` value is invalid - these should throw an AttributeError because the `__dict__` attribute doesn't exist for `inst`. In `pickle.py`, if `state` is falsey but not None code is never run to check that `inst` is a valid object (but it does happen in the C accelerator).

Author: Legoclones

Lib/test/pickletester.py

@@ -1024,6 +1024,14 @@ def test_zero_padded_integers(self):
         self.assertEqual(self.loads(b'L010L\n.'), 10)
         self.assertEqual(self.loads(b'L-010L\n.'), -10)
 
+    def test_load_build_falsey_state(self):
+        self.assertRaises(AttributeError, self.loads, b']]b.')
+        self.assertRaises(AttributeError, self.loads, b']K\x00b.')
+        self.assertRaises(AttributeError, self.loads, b'])b.')
+        self.assertRaises(AttributeError, self.loads, b']}b.')
+        self.assertRaises(AttributeError, self.loads, b']\x8fb.')
+        self.assertRaises(AttributeError, self.loads, b']\x89b.')
+
     def test_nondecimal_integers(self):
         self.assertRaises(ValueError, self.loads, b'I0b10\n.')
         self.assertRaises(ValueError, self.loads, b'I0o10\n.')