Libxslt is confused when XSLT and XML use the same prefix with different
URI.

The following stylesheet adds attribute "y:foo" to each element, the
full name of the attribute is "{y:y:y}foo".

[code]
<x:stylesheet
  xmlns:x = "http://www.w3.org/1999/XSL/Transform"
  xmlns:y = "y:y:y"
  version = "1.0">
<!-- -->

<x:template match="node()|@*">
	<x:copy>
		<x:attribute name="y:foo">bar</x:attribute>
		<x:apply-templates select="node()|@*"/>
	</x:copy>
</x:template>

</x:stylesheet>
[/code]

Apply the stylesheet to the following XML.

[code]
<a xmlns:y="y2:y2:y2">
	<b y:white="white">
		<c y:black="black"/>
	</b>
</a>
[/code]

Result is the following.

[code]
<?xml version="1.0"?>
<a xmlns:y="y2:y2:y2" y:foo="bar">
        <b y:foo="bar" y:white="white">
                <c y:foo="bar" y:black="black"/>
        </b>
</a>
[/code]

The full name of the "foo" attribute is "{y2:y2:y2}foo", but should be
"{y:y:y}foo".

By the way, saxon generates the following:

[code]
<?xml version="1.0" encoding="utf-8"?>
<a xmlns:y="y2:y2:y2" xmlns:y.5="y:y:y" y.5:foo="bar">
        <b y.5:foo="bar" y:white="white">
                <c y.5:foo="bar" y:black="black"/>
        </b>
</a>
[/code]