Don't try to use unsupported DB versions.
diff --git a/Modules/Setup.dist b/Modules/Setup.dist
index b4635cc..d24fef4 100644
--- a/Modules/Setup.dist
+++ b/Modules/Setup.dist
@@ -396,7 +396,12 @@
# Sleepycat Berkeley DB interface.
#
# This requires the Sleepycat DB code, see http://www.sleepycat.com/
-# The minimum supported version of that library is 3.0.
+# The earliest supported version of that library is 3.0, the latest
+# supported version is 4.0 (4.1 is specifically not supported, as that
+# changes the semantics of transactional databases). A list of available
+# releases can be found at
+#
+# http://www.sleepycat.com/update/index.html
#
# Edit the variables DB and DBLIBVERto point to the db top directory
# and the subdirectory of PORT where you built it.