util.datamapper: Deal with locally built stanzas missing xmlns So the problem is that xmlns is not inherited when building a stanza, and then :get_child(n, ns) with an explicit namespace does not find that such child tags. E.g. local t = st.stanza("foo", { xmlns = "urn:example:bar" }) :text_tag("hello", "world"); assert(t:get_child("hello", "urn:example:bar"), "This fails"); Meanwhile, during parsing (util.xmppstream or util.xml) child tags do get the parents xmlns when not overriding them. Thus, in the above example, if the stanza is passed trough `t = util.xml.parse(tostring(t))` then the assert succeeds. This change makes it so that it leaves out the namespace argument to :get_child when it is the same as the current/parent namespace, which behaves the same for both built and parsed stanzas.