Reverse DNS for non-maas RFC1918 zones fails inside maas

I have a maas instance that owns 172.23.4.0/24.
I also have non-maas machines on 172.21.0.0/24 (etc.).

The version of bind in the current version of maas (currently on the latest 2.9 snap, but this has been like this for awhile) maps rfc1918 zones like 0.21.172.in-addr.arpa to an empty zone instead of forwarding them. This breaks reverse DNS lookups done by maas hosts for addresses of non-maas hosts on these other private subnets. (Forward DNS still works OK.)

This can be fixed with something like this:

--- /var/snap/maas/current/bind/named.conf.orig 2020-12-14 11:12:16.135580193 -0500
+++ /var/snap/maas/current/bind/named.conf 2020-12-14 11:12:18.679606308 -0500
@@ -11,6 +11,7 @@
     session-keyfile "/var/snap/maas/current/bind/session.key";
     auth-nxdomain no;
     listen-on-v6 { any; };
+ empty-zones-enable no;
     include "/var/snap/maas/current/bind/named.conf.options.inside.maas";
 };

Can we get this patch upstream so automatic snap updates won't revert it? Blocking reverse lookups of RFC 1918 zones in maas, which is almost certainly forwarding to another internal DNS server (which can block these zones if appropriate) doesn't seem useful, and breaks some configs.