This test has the following assertions.

         <all-of>
            <assert-xml><![CDATA[<out>Printing.</out>]]></assert-xml>
            <assert-message>
               <assert-xml><![CDATA[AVT with value 'no' in @terminate of xsl:message]]></assert-xml>
            </assert-message>
            <assert-message>
               <assert-xml><![CDATA[AVT with value 'no' in @terminate of xsl:message]]></assert-xml>
            </assert-message>
         </all-of>

The actual XML produced contains a whitespace text node before the <out> start tag.  

If we assume that assert-xml requires a valid XML document, then this whitespace will be discarded by canonicalization.  However, that means that the <assert-xml> for the messages cannot be correct - they contain only text.

If we assume that assert-xml can handle fragments, then the expected first assert-xml should include the whitespace, and we have to use a canonicalizer which can handle fragments (not defined by the XML Canonicalization 1.0 spec).