--- a/mercurial/mail.py	Thu Aug 09 20:57:27 2018 -0400
+++ b/mercurial/mail.py	Thu Aug 09 21:04:15 2018 -0400
@@ -220,7 +220,7 @@
 
     cs = ['us-ascii', 'utf-8', encoding.encoding, encoding.fallbackencoding]
     if display:
-        return mimetextqp(s, subtype, 'us-ascii')
+        cs = ['us-ascii']
     for charset in cs:
         try:
             s.decode(pycompat.sysstr(charset))