The Tor Browser / file revision

 <?xml version="1.0"?>

 <?xml-stylesheet type="text/xml" href="#bug"?>

 <!DOCTYPE doc [

 <!ATTLIST xsl:transform

   id	ID	#REQUIRED>

 ]>

 <doc>

   <xsl:transform 

     xmlns:xsl="http://www.w3.org/1999/XSL/Transform"

     version="2.0"

     id="bug">

     <xsl:key name="k0" match="e2" use="name('foo')" /> 

     <xsl:template name="t1" match="/">

       <xsl:element name="e2" namespace="{//doc}" />

     </xsl:template>

     <xsl:template name="t2" match="key('k0', 'bar')" />

   </xsl:transform>

   <e2/>

 </doc>