GH-130614: pathlib ABCs: retain original separator in `with_name()` (#130990)

In `pathlib.types._JoinablePath.with_name()`, retain any alternative path
separator preceding the old name, rather stripping and replacing it with a
primary separator. As a result, this method changes _only_ the name.

diff --git a/Lib/pathlib/types.py b/Lib/pathlib/types.py
index cfdbc89644a24a023c99138d7dc4d33e7e2e0be5..c65e4e3ede90b1b17f541e76f9ce7a0c61faa5d5 100644 (file)
--- a/Lib/pathlib/types.py
+++ b/Lib/pathlib/types.py
@@ -135,7 +135,9 @@ class _JoinablePath(ABC):
         split = self.parser.split
         if split(name)[0]:
             raise ValueError(f"Invalid name {name!r}")
-        return self.with_segments(split(str(self))[0], name)
+        path = str(self)
+        path = path.removesuffix(split(path)[1]) + name
+        return self.with_segments(path)
 
     def with_stem(self, stem):
         """Return a new path with the stem changed."""