[ #315434 ] Update to top-level repeat control nodeset causes exception if the nodeset refers to a preceding top-level variable

gistfile1.html

<xh:html xmlns:xh="http://www.w3.org/1999/xhtml"
         xmlns:xf="http://www.w3.org/2002/xforms"
         xmlns:ev="http://www.w3.org/2001/xml-events"
         xmlns:xxf="http://orbeon.org/oxf/xml/xforms">
    <xh:head>
        <xf:model>
            <xf:instance>
                <values>
                    <value>1</value>
                </values>
            </xf:instance>

            <xf:action ev:event="xforms-ready">
                <xf:insert nodeset="*"/>
            </xf:action>
        </xf:model>
    </xh:head>
    <xh:body>
        <xxf:variable name="values" select="value"/>
        <xf:repeat id="my-repeat" ref="$values"/>
    </xh:body>
</xh:html>