[Python-checkins] bpo-41661: Document os.path.relpath() exception on Windows with different drives (GH-25346)

[miss-islington]

https://github.com/python/cpython/commit/de06baa9de109a00c26de0dc5a248fe7aafe09f5
commit: de06baa9de109a00c26de0dc5a248fe7aafe09f5
branch: 3.9
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: miss-islington <31488909+miss-islington at users.noreply.github.com>
date: 2021-04-12T09:03:08-07:00
summary:

bpo-41661: Document os.path.relpath() exception on Windows with different drives (GH-25346)

(cherry picked from commit 67c0b3d89c4da9750fdb43fc66d3924681b22d2e)

Co-authored-by: Zackery Spytz <zspytz at gmail.com>

files:
M Doc/library/os.path.rst

diff --git a/Doc/library/os.path.rst b/Doc/library/os.path.rst
index 251df4d516eb5..d2fe494352453 100644
--- a/Doc/library/os.path.rst
+++ b/Doc/library/os.path.rst
@@ -366,7 +366,8 @@ the :mod:`glob` module.)
    Return a relative filepath to *path* either from the current directory or
    from an optional *start* directory.  This is a path computation:  the
    filesystem is not accessed to confirm the existence or nature of *path* or
-   *start*.
+   *start*.  On Windows, :exc:`ValueError` is raised when *path* and *start*
+   are on different drives.
 
    *start* defaults to :attr:`os.curdir`.