Sync pre-release CPython 3.15 branch from GitHub (2026-09-04)

Summary:
Imported python/cpython `3.15.0rc2+dev` from upstream rev [`0ca288a`](https://www.github.com/python/cpython/commit/0ca288a8cec08f04314d2b320549cf8ae299419c) (committed 2026-09-04 14:29:34+00:00).

# Commit Info

- Base: (`3.15.0rc2+dev`) - [`6409b1e`](https://www.github.com/python/cpython/commit/6409b1e8548ae7cb5dcca0d971653d574254ec1f) (commit date: 2026-09-03 05:53:13+00:00)
- Imported: (`3.15.0rc2+dev`) - [`0ca288a`](https://www.github.com/python/cpython/commit/0ca288a8cec08f04314d2b320549cf8ae299419c) (commit date: 2026-09-04 14:29:34+00:00)

Reviewed By: itamaro

Differential Revision: D118923641

fbshipit-source-id: 01c2c68cf200eff19a26e26dea7dc3bfee481684

Author: generatedunixname1734921407115435

Doc/library/sys.rst

@@ -1485,11 +1485,24 @@ always available. Unless explicitly noted otherwise, all variables are read-only
 .. data:: lazy_modules
 
    A :class:`set` of fully qualified module name strings that have been lazily
-   imported in the current interpreter but not yet loaded.  When a
-   lazily imported module is accessed for the first time, its name is removed
-   from this set.
+   imported in the current interpreter but not yet loaded.
+   When a lazily imported module is accessed for the first time, its name is
+   typically removed from this set.
 
-   This attribute is intended for debugging and introspection.
+   The set may contain some additional strings.
+   It is intended for debugging and introspection, and consumers are expected
+   to verify each entry's status.
+
+   .. impl-detail::
+
+      Currently, :data:`!lazy_modules` may also contain:
+
+      * names of *attributes* (non-modules), such as ``"pathlib.Path"`` after
+        running ``lazy from pathlib import Path``, and
+      * names of items than have already been accessed.
+
+      In future versions of Python, these may be removed, and/or additional
+      extras may be added.
 
    See also :func:`set_lazy_imports` and :pep:`810`.