We use the "Prepare an environment for the run" option to run scripts prior to SCM checkout. However, the WORKSPACE environment variable is not set when those scripts run and I cannot find any way to discover what the workspace will eventually be. For example, if the project is set to allow concurrent builds and the workspace will have "@3" appended to the path, that information is inaccessible. This means our scripts that sanitize the git folders on the slave have to make some dangerous assumptions about where to run.

I'm not very familiar with the Jenkins code, but from what I can tell the workspace is "leased" in AbstractBuild$AbstractBuildExecution.run() just before the call to prepareWorkspace(). If the WORKSPACE variable were added to the environment at that point, I think it would be visible from any scripts running before SCM checkout.

Would it be possible to add this?