Close #14095: type.__new__() doesn't remove __qualname__ key from the class

dict anymore if the key is present. Reject also non-string qualified names.
And fix reference leaks in type.__new__().

Lib/test/test_descr.py

@@ -4474,6 +4474,16 @@ order (MRO) for bases """
         self.assertEqual(float.real.__qualname__, 'float.real')
         self.assertEqual(int.__add__.__qualname__, 'int.__add__')
 
+    def test_qualname_dict(self):
+        ns = {'__qualname__': 'some.name'}
+        tp = type('Foo', (), ns)
+        self.assertEqual(tp.__qualname__, 'some.name')
+        self.assertEqual(tp.__dict__['__qualname__'], 'some.name')
+        self.assertEqual(ns, {'__qualname__': 'some.name'})
+
+        ns = {'__qualname__': 1}
+        self.assertRaises(TypeError, type, 'Foo', (), ns)
+
 
 class DictProxyTests(unittest.TestCase):
     def setUp(self):
@@ -4491,7 +4501,7 @@ class DictProxyTests(unittest.TestCase):
         keys = list(it)
         keys.sort()
         self.assertEqual(keys, ['__dict__', '__doc__', '__module__',
-            '__weakref__', 'meth'])
+                                '__qualname__', '__weakref__', 'meth'])
 
     @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
                         'trace function introduces __local__')
@@ -4500,7 +4510,7 @@ class DictProxyTests(unittest.TestCase):
         it = self.C.__dict__.values()
         self.assertNotIsInstance(it, list)
         values = list(it)
-        self.assertEqual(len(values), 5)
+        self.assertEqual(len(values), 6)
 
     @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
                         'trace function introduces __local__')
@@ -4511,7 +4521,7 @@ class DictProxyTests(unittest.TestCase):
         keys = [item[0] for item in it]
         keys.sort()
         self.assertEqual(keys, ['__dict__', '__doc__', '__module__',
-            '__weakref__', 'meth'])
+                                '__qualname__', '__weakref__', 'meth'])
 
     def test_dict_type_with_metaclass(self):
         # Testing type of __dict__ when metaclass set...