Those were broken since 9e797c1b17 as they
always used the basic PubSub namespace, i.e. without a fragment. Which
resulted in e.g. delete requests look like
<iq to="pubsub.ec-xmpp" id="2GAeW-75" type="set">
<pubsub xmlns="http://jabber.org/protocol/pubsub">
<delete node="2e92d38c-9e90-47f6-8e26-330d25ebe96b"/>
</pubsub>
</iq>
when the namespace should be in fact
http://jabber.org/protocol/pubsub#owner
add4ff5b5a