Not all the Jenkins environment variables and build variables are being made available to the EnvInject script. When testing with version 1.19, we had JOB_NAME, EXECUTOR_NUMBER, and GIT_BRANCH to name a few. With 1.20 and 1.22, we still have JOB_NAME, but EXECUTOR_NUMBER and GIT_BRANCH are not available.
I have attached a config.xml for use on a Windows slave. The same issue exists on a Linux slave. The Git repository referenced in the config.xml could be anything. The repository referenced is just there so that there is some Git-related piece in the job.