Use http://archive.apache.org/dist/tomcat/tomcat-6/v${jbosstools.test.tomcat.version.6}/bin/apache-tomcat-${jbosstools.test.tomcat.version.6}.zip

as usual apache mirrors only keep last 2 releases. It means next release of tomcat 6(.0.42) will make the tests fail.

The archives site doesn't contain the very last release (relies on mirrors for that) but keep all previous releases, so it's a more robust solution