If environment variables is used in any of the fields that supports it, thoes fields will change with the expanded value when running a build.

E.g. If the job is configured with:

Path to exec files:
targets/${TARGET}/*.exec

Running a build with TARGET set to "dummy", the configuration afterwards will be:

Path to exec files:
targets/dummy/*.exec

This is fixed in pull request:
https://github.com/jenkinsci/jacoco-plugin/pull/94