#10686: recode non-ASCII headers to 'unknown-8bit' instead of ?s.

This applies only when generating strings from non-RFC compliant binary
input; it makes the existing recoding behavior more consistent (ie:
now no data is lost when recoding).
diff --git a/Misc/NEWS b/Misc/NEWS
index 5361574..8c7c7fd 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -40,6 +40,10 @@
 Library
 -------
 
+- Issue #10686: the email package now :rfc:`2047`\ -encodes headers with
+  non-ASCII bytes (parsed by a Bytes Parser) when doing conversion to
+  7bit-clean presentation, instead of replacing them with ?s.
+
 - email.header.Header was incorrectly encoding folding white space when
   rfc2047-encoding header values with embedded newlines, leaving them
   without folding whitespace.  It now uses the continuation_ws, as it