Issue #12021: Make mmap's read() method argument optional. Patch by Petri
Lehtinen.
diff --git a/Misc/ACKS b/Misc/ACKS
index 08fc572..900fae7 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -548,6 +548,7 @@
 Kip Lehman
 Joerg Lehmann
 Robert Lehmann
+Petri Lehtinen
 Luke Kenneth Casson Leighton
 Marc-Andre Lemburg
 John Lenton