XSLT import/include errors

It looks like XSLT also got cut in functionality in C3. I tried to rerun
old XSL stylesheets with new C3 and gave up.

The error says nothing meaningful:

<exception-report class="org.apache.cocoon.pipeline.SetupException"
timestamp="Thu, 20 Jun 2013 19:58:23 +0200"><message>Impossible to read
XSLT from 'javax.xml.transform.stream.StreamSource@cba24d', see nested
exception</message><cause>Could not compile
stylesheet</cause><stacktraceCause>javax.xml.transform.TransformerConfigurationException:
Could not compile stylesheet
    at
com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl.newTemplates(Unknown
Source)
    at
org.apache.cocoon.sax.component.XSLTTransformer.load(XSLTTransformer.java:216)
    at
org.apache.cocoon.sax.component.XSLTTransformer.load(XSLTTransformer.java:165)
    at
org.apache.cocoon.sax.component.XSLTTransformer.setConfiguration(XSLTTransformer.java:264)
    at
org.apache.cocoon.sitemap.InvocationImpl.installComponent(InvocationImpl.java:257)
    at

It looks like there is a problem with xsl:import/xsl:include from the main
xsl stylesheet.
Moreover I found that when <xsl:template match="RootElement" is not in the
main XSL stylesheet the same error appears.

Can we switch on more debugging info what is wrong ?

Greetings,
Greg