bpo-41889: [Enum] fix multiple-inheritance regression (GH-22487) (GH-23673)

(cherry picked from commit c266736ec1)

Lib/test/test_enum.py

@@ -1998,6 +1998,32 @@ class TestEnum(unittest.TestCase):
             REVERT_ALL = "REVERT_ALL"
             RETRY = "RETRY"
 
+    def test_multiple_mixin_inherited(self):
+        class MyInt(int):
+            def __new__(cls, value):
+                return super().__new__(cls, value)
+
+        class HexMixin:
+            def __repr__(self):
+                return hex(self)
+
+        class MyIntEnum(HexMixin, MyInt, enum.Enum):
+            pass
+
+        class Foo(MyIntEnum):
+            TEST = 1
+        self.assertTrue(isinstance(Foo.TEST, MyInt))
+        self.assertEqual(repr(Foo.TEST), "0x1")
+
+        class Fee(MyIntEnum):
+            TEST = 1
+            def __new__(cls, value):
+                value += 1
+                member = int.__new__(cls, value)
+                member._value_ = value
+                return member
+        self.assertEqual(Fee.TEST, 2)
+
     def test_empty_globals(self):
         # bpo-35717: sys._getframe(2).f_globals['__name__'] fails with KeyError
         # when using compile and exec because f_globals is empty