Clear data so random memory does not get freed.  Will backport.
diff --git a/Misc/NEWS b/Misc/NEWS
index 83f3da1..87379b1 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -636,6 +636,8 @@
 Extension Modules
 -----------------
 
+- Bug #1721309: prevent bsddb module from freeing random memory.
+
 - Bug #1686475: Support stat'ing open files on Windows again.
 
 - Patch #1185447: binascii.b2a_qp() now correctly quotes binary characters