Looks like a bug with xsl:copy-of when copying node-set with many namespaces.

I use following stylesheet and xml:

----t1.xsl----
<?xml version="1.0"?>
<xsl:stylesheet 
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
    xmlns:ex="http://www.example.org/"
    version="1.0"
    >

<xsl:output method="xml" />

<xsl:template match="/">
<xsl:copy-of select="/" />
</xsl:template>

</xsl:stylesheet>
---/t1.xsl---


---t1.xml---
<?xml version="1.0"?>
<root
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
    xmlns:ex="http://www.example.org/"
    >
</root>
---/t1.xml---


When apply t1.xsl on t2.xsl I got:

xsltproc t1.xsl t1.xml
<?xml version="1.0"?>
<root xmlns:ex="http://www.example.org/">
</root>

but expect got t1.xml as-is.

Looks like libxslt skip some "default" namespaces.

Versions:
Using libxml 20506, libxslt 10027 and libexslt 718
xsltproc was compiled against libxml 20504, libxslt 10027 and libexslt 718
libxslt 10027 was compiled against libxml 20504
libexslt 718 was compiled against libxml 20504

If need, I cen rebuild libxslt agains libxml2-2.5.6.