Bootloader bug with DOMBuilder: java.lang.LinkageError: loader constraint violation: loader previously initiated loading for a different type with name "org/w3c/dom/NodeList"

I've encountered buggy behavior with Groovy 1.6.6 and 1.7-rc-1:

import groovy.xml.DOMBuilder

def filePath = "MestaXml.log";
def doc = DOMBuilder.parse(new FileReader(filePath));
def docElm = doc.documentElement;

$ groovy SaveTransformer.groovy
Caught: java.lang.LinkageError: loader constraint violation: loader (instance of <bootloader>)
previously initiated loading for a different type with name "org/w3c/dom/NodeList"
at SaveTransformer.run(SaveTransformer.groovy:5)

However, if I compile the class and run with java, it's fine:

$ groovyc SaveTransformer.groovy
$ java -cp .;groovy-all-1.6.6.jar SaveTransformer
$

For the case the XML file was needed:
http://ondra.zizka.cz/stranky/programovani/java/groovy-dombuilder-bug.texy