Note that upgrades to a given release uses the upgrader from that release. As a result, there's no need to SRU this to Xenial, since Xenial-to-Bionic upgrades will use the one from Bionic.
Note that upgrades to a given release uses the upgrader from that release. As a result, there's no need to SRU this to Xenial, since Xenial-to-Bionic upgrades will use the one from Bionic.