I got this working by changing the classpath to
<path id="https://stackoverflow.com/questions/7251098/catalina-ant-classpath">
<!-- We need the Catalina jars for Tomcat -->
<!-- * for other app servers - check the docs -->
<fileset dir="${appserver.lib}">
<include name="catalina-ant.jar"/>
<include name="tomcat-coyote.jar"/>
<include name="tomcat-util.jar"/>
</fileset>
<fileset dir="${appserver.home}/bin">
<include name="tomcat-juli.jar"/>
</fileset>
</path>