bpo-30057: Fix potential missed signal in signal.signal(). (#4258)

Bug report and patch by Jeroen Demeyer.
diff --git a/Misc/ACKS b/Misc/ACKS
index 1bd3c04..0511390 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -362,6 +362,7 @@
 Arnaud Delobelle
 Konrad Delong
 Erik Demaine
+Jeroen Demeyer
 Martin Dengler
 John Dennis
 L. Peter Deutsch