fixed by making the classloader used by checkForkedPath behave like a real forked classpath, thus completely isolated from the launching jvm

fixed by making the classloader used by checkForkedPath behave like a real forked classpath, thus completely isolated from the launching jvm

reverts a small part of 845c2c5

the File constructor seems to be unable to parse URLs created from
URIs sometimes, leading to a test failure. Most likely the spaces or
parentheses inside of the path of the jenkins workspaces are
responsible.

classes from ant-launcher.jar cannot load classes from ant.jar because
of the way we structure classloaders.

This reverts part of 66d7986