If you want to override the location of parts of JBoss some of these
configurations take both a directory and a url.

You have to override both to make it work properly.

e.g.
[ejort@htimes2 bin]$ ./run.sh -Djboss.server.base.dir=/tmp -Djboss.server.base.url=file:/tmp

If there is no easy way to identify which one was specified by the user,
we should give one of the priority and choose one of them to always be initialised
from the other. Probably the dir from url?

Such a change needs to be careful not to break netboot.