From 68dbfa28d24e50fdd04db8ceaa0dcb3834e180be Mon Sep 17 00:00:00 2001
From: hauntsaninja <>
Date: Sun, 17 May 2020 21:48:03 -0700
Subject: [PATCH] bpo-13601: Mention stderr's line buffering in What's New

---
 Doc/whatsnew/3.9.rst | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index 479c33b4a7fa1c..66e7c6461ecd73 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -542,6 +542,10 @@ most platforms.  On Fedora and SuSE, it is equal to ``"lib64"`` on 64-bit
 platforms.
 (Contributed by Jan Matějek, Matěj Cepl, Charalampos Stratakis and Victor Stinner in :issue:`1294959`.)
 
+Previously, :attr:`sys.stderr` was block-buffered when non-interactive. Now
+``stderr`` defaults to always being line-buffered.
+(Contributed by Jendrik Seipp in :issue:`13601`.)
+
 
 typing
 ------