Transformation of namespace unaware StAX input leads to a wrong result.

This is the example to reproduce:

Source:
=======
<?xml version="1.0"?>
<envelope xmlns="http://www.sap.com/myns" xmlns:sap="http://www.sap.com/myns">
  <sap:row sap:attrib="a">1</sap:row>
  <row attrib="b">2</row>
  <row sap:attrib="c">3</row>
</envelope>

Stylesheet:
===========
<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  <xsl:template match="/">
    <xsl:variable name="Counter" select="count(//row)"/>
    <xsl:variable name="AttribCounter" select="count(//@attrib)"/>
    <Counter><xsl:value-of select="$Counter"/></Counter>
    <AttribCounter><xsl:value-of select="$AttribCounter"/></AttribCounter>
  </xsl:template>
</xsl:stylesheet>

Expected result of transformation without namespace support:
===================================================================
<?xml version="1.0" encoding="UTF-8"?><Counter>3</Counter><AttribCounter>3</AttribCounter>

Actual result of transformation of StAX source without namespace support:
===================================================================
<?xml version="1.0" encoding="UTF-8"?><Counter>2</Counter><AttribCounter>3</AttribCounter>