Issue #26045: Merge http.client error addition from 3.5

diff --cc Lib/http/client.py
Simple merge

diff --cc Misc/NEWS
index 7a198d61341da213cb89c0992a8a67b8da6e7389,29a09d756af3136287f91a54ad056ace0cc32b2a..efeff0a7cca4b3e68100da243b81398cc915365e
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -170,9 -73,9 +170,12 @@@ Core and Builtin
  Library
  -------
  
+ - Issue #26045: Add UTF-8 suggestion to error message when posting a
+   non-Latin-1 string with http.client.
+ 
 +- Issue #26039: Added zipfile.ZipInfo.from_file() and zipinfo.ZipInfo.is_dir().
 +  Patch by Thomas Kluyver.
 +
  - Issue #12923: Reset FancyURLopener's redirect counter even if there is an
    exception.  Based on patches by Brian Brazil and Daniel Rocco.