#15249: Mangle From lines correctly when body contains invalid bytes.

Fix by Colin Su.  Test by me, based on a test written by Petri Lehtinen.
diff --git a/Misc/ACKS b/Misc/ACKS
index 7f22360..a46ee84 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -915,6 +915,7 @@
 Dan Stromberg
 Daniel Stutzbach
 Andreas Stührk
+Colin Su
 Pal Subbiah
 Nathan Sullivan
 Mark Summerfield