GH-124985: Document that `pathlib.Path.copy()` uses copy-on-write. (#125861)

diff --git a/Doc/library/pathlib.rst b/Doc/library/pathlib.rst
index b6fb36554f7cec7dd10afb49d61d395ef0dce1c7..a42ac1f8bcdf717d7428a3ea4f67353d65f14c76 100644 (file)
--- a/Doc/library/pathlib.rst
+++ b/Doc/library/pathlib.rst
@@ -1592,6 +1592,11 @@ Copying, moving and deleting
    This argument has no effect when copying files on Windows (where
    metadata is always preserved).
 
+   .. note::
+      Where supported by the operating system and file system, this method
+      performs a lightweight copy, where data blocks are only copied when
+      modified. This is known as copy-on-write.
+
    .. versionadded:: 3.14