Revert UserDict.__init__ changes, new passing test of UserList

Lib/collections/__init__.py

@@ -1073,11 +1073,26 @@ class ChainMap(_collections_abc.MutableMapping):
 class UserDict(_collections_abc.MutableMapping):
 
     # Start by filling-out the abstract methods
-    def __init__(self, dict=None, /, **kwargs):
+    def __init__(*args, **kwargs):
+        if not args:
+            raise TypeError("descriptor '__init__' of 'UserDict' object "
+                            "needs an argument")
+        self, *args = args
+        if len(args) > 1:
+            raise TypeError('expected at most 1 arguments, got %d' % len(args))
+        if args:
+            dict = args[0]
+        elif 'dict' in kwargs:
+            dict = kwargs.pop('dict')
+            import warnings
+            warnings.warn("Passing 'dict' as keyword argument is deprecated",
+                          DeprecationWarning, stacklevel=2)
+        else:
+            dict = None
         self.data = {}
         if dict is not None:
             self.update(dict)
-        if kwargs:
+        if len(kwargs):
             self.update(kwargs)
 
     def __len__(self):

Lib/test/test_userlist.py

@@ -27,8 +27,6 @@ class UserListTest(list_tests.CommonTest):
             for j in range(-3, 6):
                 self.assertEqual(u[i:j], l[i:j])
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_slice_type(self):
         l = [0, 1, 2, 3, 4]
         u = UserList(l)