${rootURL} should be used to locate env-vars.html, since otherwise the link will be broken when the builder is configured from a job inside a folder.

[FIXED JENKINS-10502] Option to make the build not fail if there is nothing to archive

[FIXED JENKINS-17177] wrong build result in post build steps after failed pre build step in maven project

based on the conversation with Weltraumschaf (the DARCS plugin maintainer)

Generally the environment is responsible for imposing a general timeout on tests.
And this timeout makes debugging more difficult.

Made the in-flight build survive the reload from the disk.

And since it's now a symlink that points to another symlink that then
points to the real stuff, we need recursive onion peeling.