merge #12147: make send_message correctly handle Sender and Resent- headers.

diff --cc Doc/library/smtplib.rst
Simple merge

diff --cc Lib/smtplib.py
index f9d1c99bb467318b0269012cb922ccab5a674571,9080e4ae57096eb3767e2e62050a94de86fbe955..b89b5a5114f05126000f7c79f1c1f9f1e568f232
mode 100755,100644..100644
--- 1/Lib/smtplib.py
--- 2/Lib/smtplib.py
+++ b/Lib/smtplib.py

diff --cc Lib/test/test_smtplib.py
Simple merge

diff --cc Misc/ACKS
index f6faa1822b0a5221d8fa3df1e441b4609d8515b6,45b4042fa9a93f10dd74f1a4d5e30c34e5834def..3fb0d9d32133cc6a71d572fda774d2cab115a187
--- 1/Misc/ACKS
--- 2/Misc/ACKS
+++ b/Misc/ACKS
@@@ -276,8 -264,8 +276,9 @@@ Jürgen A. Erhar
  Michael Ernst
  Ben Escoto
  Andy Eskilsson
 +André Espaze
  Stefan Esser
+ Nicolas Estibals
  Stephen D Evans
  Carey Evans
  Tim Everett

diff --cc Misc/NEWS
Simple merge