gh-74033: Fix bug when Path takes and ignores **kwargs

Lib/pathlib.py

@@ -1071,6 +1071,9 @@ def __new__(cls, *args, **kwargs):
         self._init()
         return self
 
+    def __init__(self, *_):
+        pass  # bpo-29847
+
     def _init(self,
               # Private non-constructor arguments
               template=None,

Lib/test/test_pathlib.py

@@ -2312,6 +2312,21 @@ def test_concrete_class(self):
         self.assertIs(type(p),
             pathlib.WindowsPath if os.name == 'nt' else pathlib.PosixPath)
 
+    def test_kwargs(self):
+        with self.assertRaisesRegex(TypeError, 'got an unexpected keyword argument'):
+            self.cls(arg=None)
+
+    def test_subclass_kwargs(self):
+        class _PathSubclass(self.cls):
+            _flavour = self.cls()._flavour
+
+            def __init__(self, *args, **kwargs):
+                self.kwargs = kwargs
+
+        _kwargs = {"a": 1, "b": 2}
+        p = _PathSubclass(**_kwargs)
+        self.assertEqual(p.kwargs, _kwargs)
+
     def test_unsupported_flavour(self):
         if os.name == 'nt':
             self.assertRaises(NotImplementedError, pathlib.PosixPath)

Misc/ACKS

@@ -844,6 +844,7 @@ Jan Kanis
 Rafe Kaplan
 Jacob Kaplan-Moss
 Allison Kaptur
+Yurii Karabas
 Janne Karila
 Per Øyvind Karlsen
 Anton Kasyanov

Misc/NEWS.d/next/Library/2020-04-18-17-45-03.bpo-29847.Uxtbq0.rst

@@ -0,0 +1 @@
+Fix bug when Path takes and ignores **kwargs