Submitting instance with required and non-relevant node

gistfile1.xml

<xhtml:html xmlns:xhtml="http://www.w3.org/1999/xhtml"
      xmlns:xforms="http://www.w3.org/2002/xforms"
      xmlns:xxforms="http://orbeon.org/oxf/xml/xforms"
      xmlns:ev="http://www.w3.org/2001/xml-events"
      xmlns:xs="http://www.w3.org/2001/XMLSchema"
      xmlns:fr="http://orbeon.org/oxf/xml/form-runner">
    <xhtml:head>
        <xhtml:title>Submitting instance with required and non-relevant node</xhtml:title>
        <xforms:model>
            <xforms:instance>
                <first-name xmlns=""/>
            </xforms:instance>
            <xforms:bind nodeset="." required="true()" relevant="false()"/>
            <xforms:submission id="submission" resource="" method="post" replace="instance"/>
        </xforms:model>
    </xhtml:head>
    <xhtml:body>
        <xforms:trigger>
            <xforms:label>Submit</xforms:label>
            <xforms:send submission="submission" ev:event="DOMActivate"/>
        </xforms:trigger>
    </xhtml:body>
</xhtml:html>