Issue #6846: bytearray.pop was returning ints in the range [-128, 128)

instead of [0, 256).  Thanks Hagen Fürstenau for the report and fix.

Lib/test/test_bytes.py

@@ -690,6 +690,8 @@ class ByteArrayTest(BaseBytesTest):
         self.assertEqual(b.pop(-2), ord('r'))
         self.assertRaises(IndexError, lambda: b.pop(10))
         self.assertRaises(OverflowError, lambda: bytearray().pop())
+        # test for issue #6846
+        self.assertEqual(bytearray(b'\xff').pop(), 0xff)
 
     def test_nosort(self):
         self.assertRaises(AttributeError, lambda: bytearray().sort())